There's a very specific bug that doesn't appear in singleplayer, only on a dedicated server.
It seems like there's a mismatch of accessories slots between client and server. Try to equip a cape in cape slot - nothing happens. Right click the cape - it appears in Ring slot. Etc. It's not MUCH of a problem, but causes other bugs.
I would love to solve it myself but I don't even know where to begin. I see there's a command for log output, but I can't find any logs.
I copied the whole config folder from my minecraft folder onto the server so every setting should be the same.
Any help with debugging this would be much appreciated. No idea if that's problem on my end or a bug in mod itself.