Duke and Virginia Tech were the was the only power 5 conference teams that didn't play. Vanderbilt ended their season at some point in January due to a combo of several injuries and COVID issues depleting the team. For most teams, there was just a couple of games either cancelled or postponed due to a COVID breakout. The NCAA tournament was played in it's entirety. Perhaps on the latter matter you are thinking of the 2020 NCAA tournament, which was cancelled as it was scheduled a couple of weeks after the beginning of the lockdown.