the type of speaker shouldnt impact anything like that. You haven’t accidentally activated the zone out on the device have you? so its pushing the master signal out to the 2nd zone, then using one of the channel faders to control the level?
I conected the sub to the main master connection using both L&R to the sub, then ive connected the sub to the 2 additional active speakers. So yes its using master signal as if it was the 2nd zone. It’s using channel 3 as the 2nd zone and using channel 3 to control the level.
I’ll have to double check the connections when i get home. Weird.