Yep, me and steela had the same problem after 7pm, when it was just us 2 we were able to play a co-op but when anyone else joined it seemed to thru us into the loading screen, even had 1 bug out and thru the whole misson only 9 enemies spawned, so was very boring and didnt even get a medal.
I also noticed a bug in the hardcore free roam, when i entered it the 1st time i went to do a gang hideout, there was no npcs. no wildlife on my way to thehideout and i couldnt summon my horse, as soon as i got into range of twin rocks it completed the hideout in 3 seconds, giving 400 xp.