[NEED HELP | SPOILERS] TLAD Random Characters not spawning

[MrBreakYoHeart]

Hi guys. First time posting here, so please excuse any mishaps I make in this post.

My problem is that I've unlocked the Random Character missions for Dave Grossman and Malc (white man icons now appear on the map), but when I go to the locations of those icons, nobody's there. No Dave Grossman, no Malc.

I've now completed the diamond heist mission for Ray Boccino, stashed his diamonds in the trash for him, and I still cannot start any Random Character missions.

I've seen two GameFAQs threads mentioning the exact same problem. They suggested keeping on with the main story, or at least wait around the area until the white man icons turn blue. I've been trying that in between every main story mission, but given the buggy nature of the Steam version, I'm starting to lose hope.

Here are the two GameFAQs threads I mentioned:
https://gamefaqs.gamespot.com/boards/955085-grand-theft-auto-iv-the-lost-and-damned/48239546
and
https://gamefaqs.gamespot.com/boards/955085-grand-theft-auto-iv-the-lost-and-damned/51564699

And these are the modifications I made to my installation (except for the radio mod):
https://steamcommunity.com/sharedfiles/filedetails/?id=921826093

I'll appreciate any help.

UPDATE: I finished the TLAD story. Nothing's changed.