Some objects can be seen through opacity.
Using sigma engine for most of the heavy lifting. I'm not sure if anything there would be causing it.
The doors and arches only are visible after crossing them.
The mobs, after moving them? I'm not sure, honestly.
Numbered Steps to Reproduce Problem:
Code Snippet (if applicable) to Reproduce Problem:
When does the problem NOT occur?
when doors are left untouched and when mobs remain in their initial location