Image Layers don't work anymore

[benraaa]

I am working on an Affinity Photo document with a lot of layers and groups. Now suddenly I can't edit images within their Pixel Layers. If I select the layer and switch to the Move Tool the image isn't selected and there are no handles shown around. Moving with keyboard arrows isn't possible as well. The same situation occurres with layers created with the Pen Tool. All other layers, e.g. Text Layers, are working normal.
This only happens in this special document, so I am sure there aren't any settings I accidentally changed. Is there any maximal file size or amount of layers an affinity document can handle? This document is about 17 MB.
The operating system is a 64-Bit Windows 10 Pro.

I would be grateful for any help since I have to finish this project as soon as possible.

Thanks a lot, benraaa

[Lee D]

Can you PM me a link to your file and I will take a look, let me now where the images are within your layer stack you are wanting to edit.

[benraaa]

Dear Lee D

Many thanks for your offered help. Right now I figured out that there was a hidden selected layer or object which I just turned off with Ctrl + D. Now my Image Layers are accessible again.
This selection was neither highlighted in the Layer Panel nor was it replaced by another selection. That's somewhat annoying for my understanding. Now since I know about it I am prepared. But I don't find it quite intuitive.

benraaa