Back when the Casino Heist DLC dropped a nasty bug was introduced where CM challenge progress (Original Heists) was only counted for whoever hosted the heist, and it reset everyone else's progress when doing Fleeca.

On late January it was fixed, but today I was helping a crew get it when progress once again was reset, this time during Humane Labs. We never died, we were the same people, we did it in order. Only the host had progress.

So PSA for everyone attempting it now: The Heists are once again glitched and the challenge unable to be completed. I noticed the same thing happened to someone else here 4 days ago, so it must have been bugged for a week.