I've updated my Witcher 3 to 1.21 and then installed Blood and Wine through the Galaxy client, and have been playing without issues the last days. Until I noticed upon opening my stash that...

MY WITCHER GEARS ARE GONE!!!!!!

I had them all mastercrafted. I did not find this out immediately 'cause the witcher gear Geralt was wearing or had in his inventory is still there, with all the visual improvements, so I didn't suspect anything.
Paying more attention I noticed that several other items were missing too, but I couldn't tell which nor I care as much.

This is the first time I write to complain about/report a bug in any Witcher game. It's not like I've lost my save games like many complain due to the lack of cloud saving in the Galaxy client (for which I've voted), but I kinda feel a bit like that. I spent days, not just finding the diagrams but the components.

I don't know if there is anything you at GOG can make to help me out with this, but I least I wanted to report it so you can look into it.

I'm actually surprised. I'm a QA and QC analyst and I've played all the Witcher games, admiring the increasing quality level they have been built upon, but this got me.

Other than this:
Cheers on the good job! Keep it like that.

So you are running through the Galaxy client, and it says it is all updated? HoS and the DLC package? Have you done a file verify? Tried to run without the Galaxy client (ie., straight from the W3 .exe)?

Strange - because, I had all the armors crafted as well - and mine are still there in my stash.

Has to be some reason for it. No mods?

Yeap, everything is updated with, HoS and the DLC package. I've also verified the files and ran the game directly without Galaxy. And no, I'm not using mods.

But I'm considering to check what mods are out there that could help me to quickly recover the sets.