Hello, i've been playing a while and I found out that I don't get any concentration when I hit enemies and I do not have any condition or else. Anybody knows how to solve it?

Thanks.

Have you by any chance equipped an amulet called the Drinking Horn or some similar? Or one called Talisman of the Unconquerable? If so, remove the amulet, save your game and then load that save - those items are bugged.