During several competitive matches on Oasis, there’s been a glitch that starts the game as a 5v6 and then has to cancel queue after several minutes saying not enough players. It auto skirmishes before the game starts.
I’ve only had this issue one time on Junkertown, but also out of the several games I’ve played this season, none have been on Junkertown. And during the one time it queued up, it made the competitive match a 5v5.
The loading screen for the competitive match with the team listings shows how many players will be active before the match begins and it’s always accurate, but also displays the 5v6 or 5v5.