It was the Warriors' G-League game that wouldn't simulate so I did some backtracking and was able to figure it out.
I mess around with the CPU rosters in MyNBA because I want them to be as accurate as possible to the real-life rosters. I had recently replaced the 2-way players on the Warriors because the players they had in my season were no longer on their real-life roster so I imported the ones that they did have. When I added the new 2-way players to the roster I assigned them to the G-Leauge. For some reason, the CPU kept assigning Moses Moody (a non 2-way player) to the G-League and that somehow messed things up. So all I had to do was assign Moses Moody back to the main roster and that allowed me to finally simulate the G-League game.
It also gave me a similar issue with the Heat's G-League team. I recently made the Heat sign Caleb Martin to a full contract because he was previously on a 2-way deal. Once again, my season wouldn't simulate to the next day and was stopped at the Heat's G-League game. I looked at the Heat's roster and the CPU again placed Caleb Martin to the G-League. I assigned him back to the Heat and was able to simulate that game.
So it seems to be an issue with non 2-way players getting sent to the G-League. If you're having this issue then look at the G-League's NBA team and see if the roster has a non 2-way player assigned to the G-League and send him back up.