1.20.1

I have 6 skills I can't unlock being vengeful parry, Bull charge, shadow step, counter attack, perfect bulwark, and dodge master

The skill I currently have are - for dodge are roll, step, and precise roll
For guard I have guard, impact guard, and parrying

When I hover over a skill that says unusable it doesn't tell me what skill I need to be able to learn it. apparently I already have the skill that I need to unlock some some of them.

I just discovered this a little bit later, a skill I already have says unusable while others that I also already have don't so I'm even more confused but know it has to be some kind of bug

some skills have prerequisites that need to be active at the time you learning the new skill, I don't remember exactly but it something like have Step equipped, then try to learn shadow step, it might be a different combination but I think I got the idea across