Update 03/19/19: Ubisoft Massive has now released a fix for the skills bug, although it comes with a small caveat.
In a post on the Ubisoft forums, a community developer explained that the team had identified “several issues” causing the problem, and has fixed the majority of them.
However, a further patch is coming later this week to resolve some remaining problems. “Until then”, reads the post, “you can try to avoid the talents EXTRA and OVERLAP which seem to be the culprit and can cause skills to act up even after maintenance, albeit still much less often.”
Source: IGN.com Update: Division 2 Skills Bug Receives First Fix