In GOG Galaxy, where I could see my progress and time for how long I'm playing witcher, I have problem, that the progress stoped showing, month ago I had 25% of progress, and after 50 more hours of playing it's still 25%, How can I fix it?

That's the achievement progress.
If you have got no achievement to unlock since then the % will still be the same.

Are you sure? Cause it was moving even when I wasn't doing something special, and after that I moved on with the plot a lot, and the last achievment I had was save Dandelion, though I alredy found out sometjing about Ciry on the Skellige. It's like I fully finished Novigrad.

I'm pretty sure.
See the icon looking like a trophy right on the left of the %?

ok then, thank you)

Same issue here. I finished the game yesterday and I don't have the achievement for complete the game in any difficult level

Achievements is still down since 1.07 release.