https://pastebin.com/JaReHw7F

Try without sponge...

We also got two crashes today caused by the same issue, also on a sponge server (running skyfactory 3).

https://gist.github.com/331ba52da12031edd3cb09817968a87b
https://gist.github.com/19c2d4ea3c5ce7e2ce12cbbafef53d2e

I built the multiblock earlier today, and both times it crashed the server immediately after I left my base (teleported to far enough away to despawn my chunks).

I am not able to remove sponge from the server that I play on.

I can't remove Sponge too... But is the same as JaSpr says, when the chunk unload.

Ok, guess I'm gonna have to install sponge and see what's up then.

All development has moved to 1.12, it should fix now.