I got stuck in a battle with no enemies during the portals event. I couldn't run away either. I'd try, and it would let me click confirm, but it wouldn't do anything past that, and wouldn't go off the confirm action pop-up.
Reloading the page and turning off the extensions I had didn't help either.

After the portals portion of the event, I was still stuck in battle and still could not run away either. A little disheartening since I had an epic Zombified Ryori run away in a previous battle, and then I couldn't participate in the event after this battle glitch occurred and thus had no more opportunities to try and find another Zombified theme after.

So, as of the time I am writing this post, I'm still stuck in a battle with no enemies from which I cannot run away from even though the event has reset to defeating Hollowed Reapers.

Whenever stuck in a battle against no enemies, you can always just skip turn on all of your pets, end turn, and the battle will end. This is universal to any battle system/location.

Were you battling in a portal area or outside when this happened?

Thank you for explaining, I wasn't aware of that solution. ^^

I was battling in the Hay Maze right near the portal when this occurred.

Hm. I'm honestly not sure what would have caused this. I can't find anything obvious in the code that'd trigger this. Sadly, until more players run into this issue and I can collect more information, there's nothing more I can do about it atm.

But yea, if this ever happens again, you can always just skip turn on all pets and then end the turn and it will end the battle.

Thank you for taking the time to look at the issue and for explaining how to escape a battle like that, I very much appreciate it. ^-^

Today During pumpkin Event I encountered a No enemy battle, it confused me for a bit but after just hitting air I won and it closed, but of note I lost all my attraction bonus for zombies. It was odd.