sspindler

I was procrastinating so I spent 15 minutes to troubleshoot the problem and fix your document. 🙂
The problem was with the layer named "Master Page" that was on several pages of your original document which didn't correspond to a master page in your document. I don't know why its presence causes the crash so Serif will have to investigate.
The way to narrow down a problem like this is to reduce the crash to the minimum number of pages and objects. I deleted all but the first page of your document and it didn't crash so I then deleted all but the first two pages and it did crash which told me the issue was with page 2. I deleted all the objects on page one and then on page two and it still crashed. The problem was the empty layer named Master Page on page 2 which was not associated with a master page. This layer was used on several pages of your document so I looked through it and deleted the layer of each of them. You can choose facing pages with this fixed version now and it will work or you can make your own fixed copy by going through your document page by page and looking for the layer named Master Page to delete.
MY22_InsidePages_Q1-fixed.afpub

When there are selection tools, I'd like to suggest that my students use Affinity Designer.