I ran into a weird problem where my horizontal alignment boxes went missing! I recorded my screen so that you can see what's going on! I don't have a recent checkpoint saved so losing those boxes means a lot of trouble for me. Please check the screen recording and let me know how I can fix it.
Yes, I can see them in the component tree! I checked-unchecked the visible button but it didn't help! Here's the aia file incase you want to take a closer look: Boi.aia - Google Drive
Is it one of the empty Horizontal Arrangements like the one I selected from the Mock area and found highlighted in the component tree?
I dislike your design approach.
Sticking book selections to Designer areas is a disaster.
They should be loaded at run time.
You should not need to go into the AI2 Designer when your book collection changes.
This should be a table driven app.