Description of the issue:

When logging into my server, I see many of my conveyor belts get rendered with seemingly random permutations of the conveyor belt models. The HWYLA display shows the correct block is in place, and it behaves as it should (e.g., an extractor extracts, a vertical belt conveys vertically, etc.). Here are a few images of what I'm seeing:

Both examples on the server at the moment happen to be switching a covered vertical conveyor belt for an angled conveyor belt, but I'll often find all sorts of random mis-matches (e.g., extracting conveyors changed to covered conveyors, convered conveyors converted to plain conveyors and vice-versa, etc.)

Versions & Modlist

• Minecraft: 1.12.2
• Forge: 14.23.4.2705
• Immersive Engineering: 0.12-84
• BiblioCraft: 2.4.3
• Full Mod List

This has been reported before, but I think I finally realized what's going on: (This is mostly a note to myself so I don't forget it before I get around to fixing it. Something similar happened to me today with the feedthroughs.) Chunk model creation is multithreaded. All conveyors use the same model instance as far as I can see. But the conveyor type being rendered is stored in an instance variable => race conditions with the wrong conveyor model being rendered (and added to the cache).