Description of the issue:

When using the windmill on a multiplayer server, placing sails on the windmill does not sync between clients, a user needs to disconnect and reconnect in order to see the sails.

Versions & Modlist

IE 0.12-89
Forge 12.23.5.2836

The issue was discovered with a long modlist, but I've reproduced it with just Forge, Immersive, and JEI.