Kodimac

Oh, my!  Forum help is amazing!  I learned how to do a screen recording and made one to share, and then saw the other posts suggesting it was the bleed setting causing the problem.  Problem solved!  Works fine with bleed off.  So, I learned a new skill AND I learned how to fix a problem!  Affinity for the win.  Thanks everyone!
Affinity Publisher 2022-05-06 10-47-04.mp4

Oh, my!  Forum help is amazing!  I learned how to do a screen recording and made one to share, and then saw the other posts suggesting it was the bleed setting causing the problem.  Problem solved!  Works fine with bleed off.  So, I learned a new skill AND I learned how to fix a problem!  Affinity for the win.  Thanks everyone!
Affinity Publisher 2022-05-06 10-47-04.mp4

I know this came up a long time ago, but never implemented. A ruler tool is the only tool missing from Affinity and I'm not sure why it hasn't been implemented yet. 
Holding shift to view distances doesn't work 100% of the time. Sometimes I'm given simple mockups as just a .jpg or .png, so I can't find the distances between anything at all.
It takes much more time trying to find the size of an object by duplicating it into another project instead of just being able to use a tape measure tool to measure it myself.
The basis is there anyways - the crop tool already shows the amount of pixels, but in order to use it you have to press RESET on it every single time.

Maybe I've just not found it yet. Is there a tool that will allow me to measure the distance between two points in my image?

I use
1/. the Rectangle Tool (U) to drag out a measurement, shown just above the cursor before you lift your finger off the mouse button.
2/. The Node Tool (P), which also displays the the measurement before you lift off the mouse button.
At this stage there is no direct equivalent to the Ruler Tool (I) on the Eyedropper Tool (I) in PS.

Toltec for the win.  Thank you so much for making me feel like the biggest dummy ever.  When you suggested this, I was annoyed because SURELY I would have noticed a scroll bar.  I have spent literally days on this and enlisted my husband and children to help me figure out where the dang crop mark option was.  I have never felt so dumb in my whole life.  Thank you for that, haha.  Sorry to have stolen time out of both yours and Lee D's days.  I've got a burning desire to take down this thread and destroy all evidence of my stupidity.  But perhaps there's another weirdo out there who will appreciate not having to be called out on their own stupidity, haha.  
 
I am loving this app more and more every time I use it.  Thanks Lee D and Toltec for your time.