I haven't tried End Portal yet as I found this out on my new 1.17 hardcore world, but:
 

Whenever I go trough a nether portal I have to quit to title and log back on to my hardcore world because the world won't render whenever I exit a portal.

This happens both ways: either going to the nether (the nether won't load) or going to the overworld (the overworld won't load).

Either way I need to quit and log back on whenever I use the damn portals, and I frequently use portals on hardcore playthroughs.