1.12.2 beta-4

Description of the Bug
When generating new terrain I constantly get "Waiting for server" in waila/one probe and all entities "freeze" i.e. doors/chests do not open/close, mobs dont move etc. and chunks do not generate.
Closing the game hangs on "closing down server" and I need to kill the process manually.

To Reproduce
Don't know, it's not consistent
I do know that removing railcraft from the pack resolves the issue.

Logs & Environment
https://paste.ee/p/KbKlJ

I only have a client log since it does not generate an error.

Hmm, i have had this issue once as well when shutting down a sp testing world. Not sure if this is related to the logic issue i've fixed in #1641

I'll add that since I removed railcraft from my pack, it has become very responsive. I had a lot of issues with world generation lag, stuttering (when moving), lighting updates, etc. I chalked them up to the pack being extensive (well, for my rig that is). I've been playing the pack for 2 weeks and had these problems from the start but I haven't had any of these problem after removing RC. Not sure if one relates to the other?

If those lag, stall, crash etc. happens with rc along, then it's railcraft's fault. wait for beta 5 and try again.

Which logic issue? I'm not seeing any code that could cause this?

i mean that client desync caused by getting wrong interface on cart death

It might be some serious desync, We don't have enough proof for this unfortunately,