So there is a bug for PC right now that if you do the first heist (the 2 person one) and on the first setup the driver of the car pulls into the garage and it freezes (the garage bug) and the other player finishes the heist falling through the floor . What happens here causes the driver to not get the progression toward the 10 mil challenge (can be confirmed by looking at stats, awards, heists, criminal master minds) but the guy who wasnt driving and fell through the floor will get the progression 1/26.
What you do to fix this is just swap drivers. I know its simple but I have heard people complaining on reddit about this and how this bug is causing them not to be able to do the 10 mil challenge. But all you have to do is dismiss the 2p heist you were on, re-host it, switch drivers so the other person can see "set up complete" while falling through the floor and the guy who got it the first time (who is now in the car) will keep his from the ORIGINAL run.
So basically
A&B do the 1st heist twice, switching the driver
C&D do the 1st heist twice, switching the driver.
This should make everybody 1/26. Hope this helps!