Everytime at 6-8 minutes? Are you doing something special at that time in game?
Should be a quite interesting trigger doing that. Try to get it to minute 1 maybe, like speeding up the game process. For debugging that's a lot easier. E.g. give yourself infinite resources, attack, jump around using sandstorm/vortex if you have to, bolt key figures and see if it's time based or something else.