Yesterday, I was doing a tower run on my level 70 musketeer, with a full team on the Eighth floor. Right before I entered the fight, I accidentally backed up into the door which caused me to begin to teleport, but in an attempt to stop myself from going down to the previous floor, I managed to run into the fight.
The fight never loaded for me, and I couldn't see my companion, teammates or enemies. However, the fight went on normally for everyone else, and according to my friends, I used Overwatch at one point as well. After the fight ended, I was able to collect chests and everything else went on normally.