Greetings!

You'll probably like to include use of the template from the Welcome to Forum: In-Game Bugs! thread, because without it, reports here will simply be moved to "insufficient information".

As for the issue, I suspect you'll simply need to do the battle again, regardless of the cause (I'm not very familiar with this one, and can't really suggest anything for why it happened or if it is working as intended with the information we have at this point).

In any case, using the template will help getting the issue at least looked at.

Good luck!