I found out how to get the progress with denise bar to decrease. All you do is go on a date then save to the next in-game day (might need to wait outside for a bit). Then she will call CJ and if you ignore the call (let it ring out, don't cancel it) the progress bar goes down.

The progress with denise will not decrease when on mission is set to 1 for some reason (same as a phonecall). Which means if you walk into a marker at the exact right time it should set on mission to 0 and start the mission.

I cant get the timing right so I gave up but I'm fairly certain this is what happened to Josh in that run where he duped one of the later sweet missions. When you RTLS denise will call you( I think It could be random though) but if you are on a mission the call just gets skipped. When you finish the mission the progress bar goes down normally.

This could all be wrong and I need to do way more testing but I cant think of any other way that Josh could have duped. It couldn't have been a phone call because its impossible to dupe any% missions with just a phone call and no trucking/quarry setup. I think another runner did the exact same dupe accidentally.