I saw that issue #1100 was closed but it's still happening.
When I saw the issue, I exited the world and opened a test world and it still happened. Then I restarted minecraft and went into the test world, and it stopped happening. I re-opened my actual world and it continued to happen there. Something about that world makes this happen and makes it reproducible.

I can go over some observations, even put my world up for download so you can test and reproduce it but it's a serious issue. Judging from how many entities were on the ground when I realized, I can make assumptions from changes I made in the world, and almost all those changes are AE2 related.

Actually Additions version: r135
Mod pack: Modern Skyblock 3 Departed Version 3.4.1.2

So, I still can't reproduce this whatsoever. Never been able to. There was no fix for it in 135, 135 was the version with the issue reported. It should probably have been resolved by 3953c8b