Crazy timing, I was just putting together the example. Unfortunately, for some reason after the update, transparency doesn't seem work at all :C
Here's the example. Mind the comments, they're for the previous version:
https://www.dropbox.com/scl/fi/rliihhcaiqynkgx6a4e3b/transbug.capx?rlkey=0ct7g1a...
Down arrow turns the camera around
1 spawns a cat in front of the 1 sign
2 spawns cats in front of the 2 sign (on the opposite side, behind the player)
3 key spawns an extra cat in front of the camera
Space offsets an object's U slightly.
Previously, if you started up the preview, then immediately spawn cats with 2, it did reproduce the bug when you turned around to look at them.
Switching the U also did indeed break everything as well.
However, I absolutely could not reproduce the layout switch bug, except under the very specific condition of spawning the extra cat, with a wait of 0 secs. And even then it was only for that image.
I tried it again in my actual project earlier (before the update, to be clear), and the bug also just... abruptly vanished. It still happened to a single object that spawns similarly to the extra cat in the example, but yesterday I swear switching between layouts broke all of them. I know I didn't touch the project or change anything because I immediately dropped it after making this post and haven't altered anything since.
Though, as I said; currently images don't seem to be loading with transparency at all. So that's the more pressing issue. Sorry to throw all this at you! I do appreciate it a lot.