Curseforge comment by vince2240:
Hi, great mod, however with the latest 1.16.5 version there seems to be a bug, the item would not be able to be combined with any helmets including vanilla. But I then installed the earliest version of the mod and it worked perfectly. I am playing with mods, over 120 currently, so it could be some interaction there.

Can'T reproduce in my local dev env, I asked him to send me a complete list of mods and the log file.