I have no picture because it all went really quickly but I was doing the Shadows in the Desert quest and I completed the Realgam Colosseum for the ninth time for the quest, I know I completed it because I went against this dude and his last mon is a Shadow Tyranitar, and I clicked fast enough to kill his Tyranitar and I even catched it, so I'm 100% sure that I completed it, but the Dungeon closed with time during the Hyperball animation, I got the "You took too much time" message and it wasn't counted as completing the dungeon.
I'm not certain if it's a bug or if the ball animation is just suppoed to finish to complete the dungeon, but I do remember times when I was fighting for legendaries in dungeon and the dungeon completed while the ball was turning and it did count it.