I beat challenge rift 116 and went back in to get a better time. When I pressed “Start Game,” I loaded into the challenge rift lobby as the barbarian from challenge rift 115.
I loaded into the challenge rift properly the first time, but after beating it and looking at the leaderboard for the rift, I decided to go back in. The wizard for challenge rift 116 was my selected character before I pressed “Start Game,” but I loaded into the game with the same move set and appearance as the barbarian from challenge rift 115. Unfortunately, I did not try to use any of the skills or try to load the rift. I immediately left the game, restarted the rift, and it loaded properly.
I tried to load into the rift a couple times and even beat the rift again, left, and came back in after looking at the leaderboards like I did the first time, but I was unable to replicate this problem.
Sorry if this is lacking in helpful information. It seems like it was just a one time random thing.