*** Update, May 2020: If you've recently started seeing YouTube ads even with AdBlock installed, YouTube may be testing some advanced ad blocking circumvention on you. We have not been able to reproduce this issue on our end, however, many of our users have reported that signing out of their YouTube account often resolves any recent issues related to YouTube ads, including seeing unblocked ads, the skip button disappearing, or seeing error messages in place of ads. (Sometimes they can sign out and sign back in, but sometimes they must remain signed out.)
This also appears to be happening to users regardless of which ad blocker they're using, which leads us to believe that YouTube is testing some new (particularly aggressive) technology on their end. Unfortunately we can't do much to get around it until they release it more fully, so we can see exactly how they're working around our ad blockers. Rest assured that we're on the case!
