@francksauzee4 I agree, I've noticed it never happens if I play all 12 then continue to refresh opponents and play (just to get Evolutions done, for instance). For me, it is always after goals. My guess is a glitch whereby the SB points are calculated for each match. Each goal adds 100 points, so I imagine something is going wrong when the goal is scored and the calculation is happening - the game just freaks out.
It would be great if all 12 were replayable (like TOTW) so if it happens we could try again (if they aren't going to get off their backsides and fix the problem they know about).