Hello everyone.
I had the same issue of roach's invisible mane and tail after installing patch v1.21,
also disappeared gear i wore and invisible Geralt after installing Blood & Wine dlc, with verify/repair!
What i did and fixed everything and using lots of mods after many tries?
I deleted the Mods folder and loaded a backuped savegame, made new save and restored the Mods folder, not sure if it was only this thing which saved my gameplay progress,
but i think it has to do that on this savegame i never had both DLCs, Hos and BaW.
Try it, it might help you too.
Good luck. ;)

I get the missing tail from time to time myself. No idea how it's triggered but i do go alt+tab very often sometimes and then its gone, not 100% sure that is actually what triggers it for me or something else. Usually loading earlier save where Roach has tail fixes it. Happend couple of times that i had to restart the whole game to fix it. I'm using only 1 mod and i've done re-,pre-installing of mods and game and still had the missing tail. But best bet is like you said to load earlier save that fixes it most of the time.