Modpack version
0.4.14
Describe the bug
So when using Create piston on private multiplayer server to push blocks, they seem to move at first, but as soon as they reach their designated place, they dissapear, losing their hitboxes and everything, yet you aren't able to pass through them. When I leave and join the server again, blocks magically appear back. When I move them again, they seem to come back, but as soon as they stop they become ghosted again.

Logs
Attached.

latest.log

Screenshots
Attached.

Thank you for the report, I will investigate the issue.

UPDATE: I found the issue. This seems to do with Quark.

I tested other mods' blocks, and it turns out only Quark blocks dissapear. I tested multiple - slate, marble, mossy cobblestone bricks, and all of them dissapear, whereas blocks from other mods just simply work.

That still doesn't explain why it does that, what's with Quark mod that makes the blocks disappear, and then appear after you join back, this seems like a client issue since I'm not getting any errors in the console anyways.

Alright, this is the same issue as #2146 then, thanks :)