Hi Vasilis,
I thought the problem was solved but after my last post I started having the same issue with my temp user. It's not a big problem, I have been working with blank icons the past weeks, it's just that it's very odd not having Capture icons on my files.
But the main reason I'm writing again today is because I just bought a new mbp 16" and after installing Capture on this new computer, new account user from scratch, what was my surprise? On this new computer runing Monterey I'm having the same blank icons!!! So now I'm I can tell there is on issue on your side or from Apple.
I'm attaching a screen shot.
Btw, I did the get info thing selecting always open this type of files with Capture. It's on my screeshot.
Hope you can fix it.
All the best,
Philippe