I finished my solo duality today and once I got done I went to claim the triumph and saw it didn't unlock. I did have two weasel errors that kicked me back to title screen during it so my guess is that's what caused it to not unlock. I did restart my router after the 2nd error code and I didn't have any issues after that. I did however unlock both "solar fireteam completion" and the "United in class" triumphs for playing on my solar titan. I checked dungeon report just to verify the solo clear there and it's a checkpoint solo clear, I know dungeon report is 3rd party so it's not official but it's the only tool I know about. I can solo it again that's not a problem just want to make sure this possible bug got reported.