I just built a test machine with some cogs & a creative engine, nothing more, not even connected to anything.
I'd usually take a screenshot but I can't load into the world anymore, it instantly crashes.

Here's the crash report: crash-2021-01-18_17.06.39-client.txt

I use a pretty large modpack, but I don't think the crash is related to any mod interactions.

This issue has been marked as stale because it has been inactive for 3 weeks. It will be closed if it remains inactive for another 3 weeks.

This issue has been closed since it has been inactive for 3 weeks since it was marked as stale.

Same issue here except with shafts. I made a small stone generator with a drill miner and had this ticking entity issue appear when I was switching render distance.
https://paste.ee/p/jEZUF
Duplicate of #779

I had a similar issue. Not sure if it is known or not. From my testing (on 1.16.4), it occurs when a chunk with a powered generator is loaded. If you turn the generator off before quitting or reloading the chunk, it seems to work fine. The only problem is that it's easy to accidently reload the chunk or just forget to turn it off.