Not only the thing with getting a mount needs fixing, after you hit 80 in core tyria you get annoying popup that appears over chat that tells you to go to expansions to unlock masteries, this also butchers story immersion. I had to go to HoT and finish first mission when I haven't done even 75 percent of core story. You can't disable that popup, it reappears every time you gain exp, it forces you to unlock masteries. In a way it's a good thing because if you wouldn't unlock them then you'd waste exp but why not just make masteries unlocked by default when someone owns expansions?