After the last last update in mid may I lost the ability to use Da Vinci and the day of the dead AI Persona (Whose name I can't seem to recall.) from previous challenges I had completed previously. The game seems to have also reset the challenge counter and is making me redo them all. For some reason though, it seems to have not effected the third challenge and it's prizes.  It took a long time to finish those challenges, so I find bug this far more disappointing than most other I have seen and reported in the past. I hope it is fixed soon and the unlocks are stabilized, so this never happens again. 

I've said in many previous comments that this was looking to be best historical strategy simulation game I played... But progress deleting bugs?! At this stage?

Yeah I have to reconsider that statement now. I'm so disappointed    

I have the same problem here, but I've lost all three persons :(