Multi-battle does not work with event dungeons
After selecting a stage in an event dungeon the multi-battle button appears normally. i click on it and the next screen appears normally. I then cloick on the button to start the multi-battle, but after the first battle, one is deducted from my available battles but the second battle does not begin and the multi-battle has ended. This only happens in event dungeons. It is happening in the current event dungeon, and happened in the one previous to it.