I play on a DW20 1.0.14 server using Hats version 2.1.0 and I had lots of hats, then one day I opened my Hats List and saw this: http://prntscr.com/2qgpcb . And 1/2 my hats had gone. I then realised all the hats in that option are the ones that I lost and somehow grouped together. I had now lost these hats and I don't think I can get them again as the game still thinks I have them in my list. I don't know if this is a bug or what, buy yeah, very annoying.

Extra Info: When I put the hat one, it acts like an invisible hat.

Can you get me your hats.dat and your username for debugging? I can't reproduce this at the moment.

Ummm my Username is 'iMarbot' but I have no idea where the hats.dat is saved, if it is saved in the world then ask Quetzi (you know from Forgecraft) (I play on his sub server) for it :) If it isnt in the world save folder then if you tell me where it is I can get it for you :)

Have you used Hats Trading in any way?

I'd have to go with "yes you have", cause I found the issue with Hats Trading. Unfortunately I can't do anything to fix your save :(

But at least it's a bug found and fixed (I think). I'll wait for your reply before closing this.

Yes I did use Hat Trading, OK, turns out that I can get the hats that have been bugged again (via mob killings), so that is good news, and I do hope you successfully managed to fix it :)

Fixed in 2.1.2