there is a bug in the invasion mode. when I reach wave 7 the enemy number locks on 7 and I cannot move on with the next wave
Sometime high level enemy could be down/dying, wait around 30 to 40 second or kill them manually
it didn't work this time it was the 5th wave and enemy number locked on. perhaps you should make a mini map that show me the remaining enemies
Update 3.12 just out, it should fix this issue :)