Often if I get too much XP at once (eg. after fishing for a few minutes) the xp bubbles get stuck around me or no more xp comes out while fishing but now the XP bar hasn't changed at all despite getting more XP. I've tried exiting, closing the application, going back in a few times. The XP will still heal tools with mending on them but the XP bar won't add any.

Hope that explanation makes sense!