Ok, i got my groups to the set of switches, and defeated the last of the dragons but back with my 1st group, they cant get through, there is no path, and with the 3rd group i checked the sparkling treasure chest which makes the conveyor belt appear and is supposed to clear the path, but still there is no way to get through....the room i cant get through in is like split down the middle, and there is a switch on the other side with no apparent way to get there.

OK, the 1st group will get out of that room with the help of your third group. It's after your 3rd group fights that monster that jumps down on you.

I figured it out, my 2nd group missed a vent which had a switch in it.