Took me some time to trigger that aswell. If I remember correct at some point in this questline I had to wait two weeks to trigger further progress even thought the walkthrough said one week. Another thing the walkthrough didn't mention, but something I needed to do, was to get Biff to level 3 (while on level 2 collecting data from the office workers and afterwards being a "good girl" for Biff increased my standing with Biff by ~8 points).The same problem for me i think, have done all other events in the update except for the photoshoot and the public event, cant get the photoshoot to trigger even after i made the last shoot once again and waited another week.. :/
The public event will happen before the last shoot. The last shoot then took me two weeks to get all picutres.