I'm fighting through the lag to finish my BQs for the day, and I keep getting "this battle does not exist" when I finish one. Usually that means I've clicked the button to end the battle too many times, but it still goes through ok. Out of curiosity, I started watching my pet's exp and it hasn't gone up for several battles. From levels 24 through 28 I have not received any experience (I've been at 4,863,760 this entire time), but Reischen still gives me my item reward and moves me up to the next level.

I've been experiencing a different issue, but still a problem with doing battle quests overall, which I detailed over here. I should probably check to see if I am even receiving my EXP :/

[edit]So it does appear I lost 6-7k EXP at some point during yesterday's quests. Lovely.

I got that a couple times, too. It should list the exp on that page and direct you back to BQs, but doesn't. I haven't gotten any 504 errors though. Just the infinite loading or "this battle doesn't exist". :/

I just wanted to mention that this is still happening and is an issue with regular battles too.

This is what I got against my eighth win against this challenger. Like Speiro mentioned, this seems to happen during times of lag when I hit the Make your turn/See results button one too many times.