If you install this mod with immersive portals it causes entities to be invisible.
This is caused by an validation that ImmersivePortals does, so I removed that validation which caused the client to only run with a maximum of 1-2 fps (on my computer) or sometimes even with 0 fps (on the computer of a friend)

Before removing the validation there was no issues on the client without the entities being invisible
https://pastebin.com/XxGkV7J1

If needed I can provide the version without the validation
(It checks if the current thread is indeed the main thread which isn't the case here)

This issue will probably require more testing as it could also be related to the location the players where at, tested in the Twilight Forest and Undergarden dimension