I've gotten all of the achievements on Xbox One and linked that ARKS account with my Steam account. Some are easy enough to repeat and others may require specialized solutions.

When I tried to get the various class-based achievements for Steam, none of them would proc even though I switched between every single class (all of which were 31 or higher). I haven't tested all of the achievements so I don't know if it's exclusive to the class level ones or not.

Did you switch between the classes by actually selecting the class from the Class Select, or did you do it via Loadouts? I found that doing it via Loadouts won't trigger the achievements.