I always save when given the choice to fight or skip. The fight ends up bugging after I have reach the 2nd turn and use skills and or magic.
My stats are maxed for that point in the story, I always buff Ise, and I always try to wipe the back line first using the Holy Lightning, Rias's skill and Ise's area of effect fire attack.
However, halfway through the 2nd turn or when I've used half the teams skills, the game bugs out, sometimes stopping just before the skill is used on the enemy, after I select it and then choose the enemy, the game just stops. I can still select characters on the board but can't do anything, not even go to next turn.
This happened every time even after reloading or quitting out and returning. So I had to fight without skills after turn 1.
I am currently not able to send a save file because I first encountered this on Android. I was going to see if it was on PC but I'm not at home and won't be for a while.