Hit a creeper through a portal, it will not teleport. It will just clip through the portal.

MC 1.15.2 Forge 31.1.46 immersive-portals-0.13(forMc1.15withForge) (from CurseForge)

I restarted MC without RandomPatches and things like dropped items, fast arrows, creepers etc. all do not teleport through any portals.

Then remove all other mods

The issue persists with NO mods except for MixinBootstrap and ImmersivePortals.

Please just test it out and see if you can reproduce the bug.

I cannot reproduce this.

I'm using OpenJDK as well. Let me see if running HotSpot fixes the issue.

Running Java jdk1.8.0_212 doesn't seem to fix the issue. I'm not really sure what else the problem could be. Do you have any ideas?

The issue still occurs on a new world, still using HotSpot VM.

The mob should teleport through. Does this happen with only this mod and mixinbootstrap installed?

Arrows teleport but only at very low speeds.

So I believe the entity teleporting code is somewhere but kind of weird.

I have Controlling, JEI, Mouse Tweaks, Inventory Tweaks, ReAuth, and RandomPatches. I think only the last one could possibly cause this behavior, if the mod usually works perfectly

Try to remove randomPatches and try again?

I'll let you know if that fixes the issue. In the meantime if randompatches is the culprit, maybe you should check it out and see if you can improve compatibility.

ok so it seems dropped items, mobs, and arrows work cross-dimension, but not through portals leading to the same dimension (short range teleport in overworld for example)

Fast moving arrows still bypass both portals tho