Currently it seems as though the TubeBuddy milestones look at either your channel's about page, or just total views on public videos to decide on your upcoming milestone. This means if you live stream and unlist the stream afterwards, those views on the stream don't count towards milestones, even though the views are still counted in YouTube studio lifetime analytics. It is the same if you unlist videos. So I think it would be great if the milestones showed your true, up to date view counts etc, by looking at your analytics instead of what is on your channel's about page/public videos.