If you start a match before 4:00 and don't finish it before 4:00 you will get an error at end of match.
No reward or Exp but Stamia is still lost !!!!
Don't start a match before 4:00 if you it you don't have time to finish it before 4:00.
It is server which refresh at 4:00 AM every day so player have to reload game.
I don't think this will be fixed. When game started there was no waring about this but after bug reports they fixed this so players get a warning if they try to start a match short before 4:00.