Hi everyone! Sorry for not replying for a while. I admit that I hadn't provided you with proper pictures and enough information. The threads seemed to be perfectly fine, at least visually. The race didn't move at all when I tried to remove it at home.
However, I managed to take it off several hours ago. I went to my LBS where they have a proper vise which I could use. Once the fork was clamped into the vise, it was a matter of applying quite some force to remove it. But it got loose in the end!
My theory got actually approved. The steerer tube got kinda expanded that's why the race wouldn't move. The guy at the shop chased the threads with a tap so the fork should be fine to use. However, when I got home I got to think whether he used the right tap for French threading
