Happening to myself as well. This is one annoying bug. After spending a lot of coin and materials to make this set after crafting the Manticore and being disappointed by the chainmail on it.
I have noticed that sometimes it won't bug out if the buff you get from the 3/6 set fades away before battle ends.
I've had to shelve this as well for now, tedious to have to keep taking the gear off or reloading a save after each combat encounter. I'd change the gear if it was my first play through, but I'm almost 200 hours played in this and I would prefer to use the GM Feline armour.
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Between being unable to take down the hood on the Grandmaster Feline chest piece (Geralt finally goes predominantly somewhere sunny and now he gets a hood... ) making Geralt look like a poor man's Assassin's Creed knock-off and the sound bug, it's really put a dampener on my 280 hours with the game.
I feel you on the hood part. Part of the reason I enjoy this game are the facial expressions. The hood covers up a lot of that, so I use the glasses from HoS. Not perfect as you lose the ability to see Geralt's eyes for the most part except seeing his eyebrows raise etc but better than having half of it concealed. I also try to think of the hood as a means to hide my disgusting face at times when I'm overloaded on decoctions / potions and it helps me live with the hood a bit when I decide to take off the glasses lol.
