firstdefence

Hi, Ive just worked out how to get round this. I have homebrew installed and installed/updated python via the terminal
 
brew install python ...it updated my python, which I believe is already installed with MacOS but I still got the clipboard error.
I opened terminal up and ran this code.
 
pip install clipboard so now I get past the clipboard error and now get the PIL error (ModuleNotFoundError: No module named 'PIL') so I used this command in terminal to get past the PIL error, after this I got the GUI.
pip install pillow  

It's as @firstdefencealready showed above, then you have to install the "clipboard" module via Python's "pip || pip3" command. - The pip command will fetch it from the Python module repository and install it ...
This script uses the following Python modules ( green = default module in Python, magenta = add-on modules to be installed via "pip" )
os  -- a default one in Python for certain OS related functions, crossplatform. clipboard -- an add-on module for being able to handle the clipboard crossplatform, has to be installed via "pip" PIL (pillow) -- an add-on module for being able to handle imaging crossplatform, has to be installed via "pip" tkinter -- a default module framework for GUI handling in Python, crossplatform. So the "clipboard" and "pillow" modules have to be installed into Python via "pip" if not already installed!

Just wanted to say thank you and I really appreciate all your efforts @v_kyr on this forum.

Hi, Ive just worked out how to get round this. I have homebrew installed and installed/updated python via the terminal
 
brew install python ...it updated my python, which I believe is already installed with MacOS but I still got the clipboard error.
I opened terminal up and ran this code.
 
pip install clipboard so now I get past the clipboard error and now get the PIL error (ModuleNotFoundError: No module named 'PIL') so I used this command in terminal to get past the PIL error, after this I got the GUI.
pip install pillow  

Just wanted to say thank you and I really appreciate all your efforts @v_kyr on this forum.

Since there seem to be a bunch of people (...probably the OP here too, at least it sounded like that to me) which are lost with terminal based CLI apps, here's GUI version out of my Python script, which I named ImagePadderGUI.py. - Since I was lazy, I reused Python's build in Tkinter GUI framework which is crossplatform and already a default part of every Python installment. - This GUI script does basically what the CLI script does, but has one two additions, like a setup to switch between the generation of new padded image files with a given/added suffix name, or instead the overwriting of the existing image files.  And a free padding color selection which is then shown as a preview on the GUIs own window canvas. Further it's also OS crossplatform usable, as the CLI one was too.
Here's a quick screencast of how that ImagePadderGUI.py looks like and how it is intended to be used ...
 

imagepadder_gui.mp4 This ImagePadderGUI.py script has to be run via Python 3 and is started like this from a console ...
... though if a Python 3 installment is available on a system it can also be made an executable script via "chmod +x ImagePadderGUI.py" and then started via double clicking etc. - Here's the script ...
ImagePadderGUI.py This script uses the following Python modules ( green = default module in Python, magenta = add-on modules to be installed via "pip" )
os  -- a default one in Python for certain OS related functions, crossplatform. clipboard -- an add-on module for being able to handle the clipboard crossplatform, has to be installed via "pip" PIL (pillow) -- an add-on module for being able to handle imaging crossplatform, has to be installed via "pip" tkinter -- a default module framework for GUI handling in Python, crossplatform. So the "clipboard" and "Pillow" modules have to be installed into Python via it's "pip" command if they are not already installed ...
 

Ok I think I found the culprit. You have an active selection, a small one in the tree above the 2 people you're adding. Deselect any selections and you should be good to go.

How have you made the mask?
 

You cannot move the symmetry back, once you move it, intentionally or accidentally there is no way to snap it back, it ignores all snapping, all you can do is place guides at the document centre, both vertically and horizontally and get as close as you can to the guides intersection by incrementally zooming in and manually moving the symmetry node/marker. The symmetry Axis point doesn't register in the transform panel either so it's not like you can reset from there either. The only thing you can do is make sure you lock the symmetry in place prior to any work. 
Affinity really should start asking their customers what they want from a feature; like symmetry. Adding a feature half ass baked just creates problems and facilitates the need for workarounds and workarounds means you failed to meet the needs of your customers. A simple reset option would certainly help but if you are going to do something do it better than anyone else.
"Function, Precision, Control, Design", NOT, to be a Royal PIA.    

We aim to please, it's called quantum solving 

You cannot move the symmetry back, once you move it, intentionally or accidentally there is no way to snap it back, it ignores all snapping, all you can do is place guides at the document centre, both vertically and horizontally and get as close as you can to the guides intersection by incrementally zooming in and manually moving the symmetry node/marker. The symmetry Axis point doesn't register in the transform panel either so it's not like you can reset from there either. The only thing you can do is make sure you lock the symmetry in place prior to any work. 
Affinity really should start asking their customers what they want from a feature; like symmetry. Adding a feature half ass baked just creates problems and facilitates the need for workarounds and workarounds means you failed to meet the needs of your customers. A simple reset option would certainly help but if you are going to do something do it better than anyone else.
"Function, Precision, Control, Design", NOT, to be a Royal PIA.    

Use the pen tool to make a clipping mask to get a nice clean edge, simply nest the image inside the pen tool created curve.

Well the OP wants to process 1000 images (in a folder) ideally automatically with a one button click. - The images have to be padded in such a way, that they have to be rounded up to the next hundreds on the longer side (w/h) via padding and the shorter side has to be equalled in size via padding here. So the whole image is afterwards padded accordingly to form a square padded image at the end. - And this up to 1000 times!

@ibideti Try opening this, I'm not sure it's all of it but it's a step in the right direction, there are 33 pages so it might be ok, the layout needs changing because it looks like you have single pages vertical. but I'm sure it's workable. 
CATALOGO - UNION Imported.afpub

Worth it for me, but not worth it for you.

Usually you don't need a graphics app with good macro capabilities (like PS) at all to do what you want. - You can do that in any better scripting or programming language easily. I show you here a quick turn around with a custom made Python script therefor.
I've used just 4 JPG images for demonstration purposes (since I'm lazy, and since it doesn't play any role if you let it process 4, 100 or 1000 files ... here) in an "test_it" subdirectory therefor. Two landscape (long side horizontal) and two portrait (long side vertical) oriented images. Then I let a Python script do all the work by pointing that to the subdirectory. The script looks into that directory, fetches and processes all the JPG-images therein, it adds the wanted rounding up for the individual image w/h and makes a padded square out of those (I used blue for the padding color, so it's better viewable here for demonstrations).
Used file sizes before padding:
img-horiz-1920.jpg  = w x h = 1920 x 1080 px
img-horiz-3444.jpg  = w x h = 3444 x 1791 px
img-vert-2048.jpg   = w x h = 1633 x 2048 px
img-vert-3333.jpg   = w x h = 2561 x 3333 px
File sizes after padding:
img-horiz-1920.jpg  = w x h = 2000 x 2000 px
img-horiz-3444.jpg  = w x h = 3500 x 3500 px
img-vert-2048.jpg   = w x h = 2100 x 2100 px
img-vert-3333.jpg   = w x h = 3400 x 3400 px
Here's a screencast of how the Python script operates then ...

padding_images.mp4
As initially said, the whole is easy to do with the right tools therefor!
 
 

Given that several other applications show the same kind of issue with your file, I think the real question is what's wrong with the file, not what's wrong with Affinity.

Okay thanks
I have been able to use the workaround that Loukash posted (saving without the alpha channel).  Still concerned but thanks for all the suggestions.

Actually, If you see an asterisk (*) inside the brackets as in next to the 32, it means your image is in a colour profile other than your working space default. If your working space is Adobe RGB and your image is too, then no asterisk, but if instead you open a file in sRGB, it will have an asterisk at the end of the title bar information to let you know about the profile mismatch. This isn't a bad thing necessarily since you could easily have opened it this way on purpose. Photoshop is just subtly letting you know about the situation.
The one outside means you have made changes but not saved yet.
 

I opened the TIFF in Preview and saved it without alpha channel.
That fixed it.
In other words, there was some data that is being falsely "moved" to alpha when opened in Photo directly.

Can we have a way of toggling the  on and off from the layer icon, having to go into the  to turn off the  is tedious.

Hi @stateofgary,
Welcome to Affinity Forums
This is a known issue that's already logged with the developers. I've bumped/updated the report to bring it to their attention again.
Thanks for reporting it though.

Thanks for the laugh