When the ropepully has moved a contraption up or down the contraption becomes invisible when it stops for the client on a server but the blocks have collision. This also happens with a gantry. Funny enough when you right click the blocks that are invisible they appear, so does relogging.
This even happens with chassis blocks.
No optifine.

Playing on a modpack: Enigmatica 6

Thanks for the report. Looking into the issue, this sadly cannot be addressed by create.
See EnigmaticaModpacks/Enigmatica6#2862 for details

executing /reload via the server console may fix this issue
but rendering problems when swapping blocks with the block zapper still persist