Before every single match in Training Grounds, I get a Something Went Wrong error before my opponent is chosen. Fortunately, I can hit retry or the back button on my phone and it proceeds as normal. Maybe this has something to do with trying to tinker with the matchmaking system?
For me is the same, even sometimes I get the Something went wrong screen twice, pressing retry button continues to the match.
I do not get an opponent in Nodes of Power - even without the Something went wrong error.