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Issue description:

When i or someone else places a reactor block, it shows an entirely different block. Only happens on a server though, and other players can see the reactor fine.

Steps to reproduce:

1.make block
2.place block
3.see wrong block.

Version (make sure you are on the latest version before reporting):

Forge: 31.2.49
Mekanism: 9.10.9
Other relevant version:
minecraft 1.15.2
Ubuntu server 18.04
client running win10
latest java (auto updating)

This also happens on biggerreactors.
https://user-images.githubusercontent.com/42798255/110262784-7a96f180-8000-11eb-824d-fb609be4c6b5.mp4

If a (crash)log is relevant for this issue, link it here: (It's almost always relevant)

Dont have a crash log.
[gist / pastebin / etc link here. Please make sure that it isn't set to expire.]

Server runs latest java with the auto updater, my pc runs this:
openjdk version "15.0.1" 2020-10-20

That's an issue with your client or the server itself. Try with Java 8, remove any hacky client-only coremods and/or don't use a hacked client

1.15 doesn't support java 15, it is only quite recently in 1.16 forge got support for java 15

i have switched back to 1.8.0, and its still not working. i would go back on the server, but it makes me think its something between the link with client <-> server.