So just did a Shadow Council Invasion. Events were done as soon as they popped, except at some point they stopped popping for about 3-4 Minutes of the Invasion, not a single event and the last one (Infernals) was definitely finished. Also for extended periods of time even on the main gate hardly anything but the odd 3~ imps spawned.
I did it mostly because it's the last one missing for the Platinum Defender, I end those invasions in other cases hundred of points above the Platinum requirement but this time we fell short exactly 3 frigging points. Coupled with no events for such an extended time for no reason whatsoever and barely no mob spawns (picked up pace at the very end, thanks a bunch for nothing).
Have had this invasion three times in the last two weeks where no mobs spawn from the back entrance. Still managed to get plat but it's pretty painful.