Every little thing will crash your client. Chests and control blocks dont work when they are part of the elevator. Doing certain things(basically anything, like placing blocks outside of the elevator) while in the elevator will crash the game. This needs to be fixed immediately. It's a good mod and when you use it to make simple single platform elevators, it's fine but as soon as you want to make a realistic elevator, it goes to shit.

I need a whole lot more information than this. please include crash reports, and preferably also screenshots of the issue.

Ill try tomorrow to post some issues, but one thing you should be able to recreate is this: go into an activated elevator in creative mode and start building outside of the elevator whie you are in it. I found it to take the block from you but leaves you with that buggy "0" block, where the block is in your inventory with an amount next to it, but the amount is 0. If you then try to place that, it crashes. I also found i was not able to link floors on more than one floor page with more than 1 command block.

Ill try to remain active on here because minus the crashes that i got from pretty much everything, i really like how the elevators themselves worked and how they operated so smoothly

i can add to this with:
Control Blocks Do Not Emit Redstone.
Elevators kinda flash in and out of existence.
Other Stuff?

Redsone emission works perfectly fine for me, what versions are you using?
Same question about your "Elevators kinda flash in and out of existence.

Thutcore: 5.19.7
Thuttech: 6.1.4
Update: It Is World Specific