Are you playing on a iphone/itouch OR PC/MAC?
If the former, have you tried, doing the "app manual shut off" thus rebooting the app?
If that didn't work, and when all else fails, I just reboot my iphone, and the app usually is fine again (with other issues of course) I've never experienced the issue your having yet
When you are done your DM go into a different room and switch back or open a new window/tab and change it in your personal settings.
Then the room had more people wanting to play 'non random'.
3 - non random.
4 - random.
The Deathmatch turns to random because the majority want it.
DM's are played according to the majority.
If more people have their setting on normal then on non-random the entire dm will be played random.
Not a bug *sigh* so many people complain about this and no one learns.