Syndicate Takedown event - bugged, or just changed?

[Saxondale]

I couldn't find anything while searching the patch notes to suggest this has changed.

 

Over the last few days I have tried running this event several times without luck, as I cannot trigger the boss fight during stage 2. As I understand and remember it, during the second phase you have to either a) set 3 bombs, b) take down 3 named bosses and their spawns, or c) rescue 4 groups of PPD

 

However, completing these tasks doesn't seem to trigger the boss and ultimately the timer runs out.

 

Here you can see I have completed the bombs task in the first screenshot, and subsequently also the named bosses in the second, plus their spans of 3 minions each. I ran out of time on the last group of PPD prisoners, but I understand it, I should have already triggered the rooftop fight after either of the previous tasks. And yes, I checked, and I could not use the elevators. 

 

User error, or bug?