I have, indeed, reset the engine multiple times at this point.
Hm… This only seems to be happening on one specific project, after converting it from 4.4.3 to 4.7.6. I tried converting a different 4.4.3 project, and that worked fine, so that doesn’t seem to be the issue.
Also, I tried making another copy of the original 4.4.3 game, and that one didn’t work either. It definitely appears to be project-specific, though I don’t know what could be causing it.
I might try 4.8 at some point, but at my current location the internet isn’t too great, so downloading takes quite a while.