Watched DG's video. Same issue.
Core i-5 6600K
Samsung 950 Pro NVME M.2 SSD
Nvidia GTX980 4GB GPU
Clean copy of GTA
Steam Version, fully legit
Already tried reinstall of GTA, client, and server
Had FiveReborn installed into clean copy of GTA Steam folder. I think I seen somewhere that FiveReborn might need to be in it's own folder inside your main GTA folder like this:
Grand Theft Auto V\Five Reborn\FiveReborn.exe
Could that be the source of this issue, or is that totally unrelated?