The game got stuck on wave 53. Might have been wave 52. Several units stopped at my leak zone and didn't pass through. The next wave did not start after they were killed. The scoreboard showed that all three remaining players still had units remaining in their lanes (so the next wave didn't start) but we had cleared them all. Additionally I could still spent gold on towers but the towers did not appear on the map. Normal difficulty with no additional modes.
Thanks for looking into this.