LegalPossessive

Did you install the EUP configs?

Have you tried starting GTA and the Rage plugin at the same time?

Have you updated GTA and the new Rockstar Games launcher?

Let the game update via Steam, which is only an update for the Rockstar Games launcher they released today. After that try doing the procedures I listed above.

GTA is updating from Steam?

Try launching GTA and Rage simultaneously in Borderless Windowed mode

Have you tried launching GTA first, then Rage hook simultaneously?

Rockstar released a games launcher today, which was a curve ball for all of us. There is a temporary fix for the moment thanks to @Idahome Samuel I will refer you to his article here: I suggest backing up your update.rpf file as the new one caused problems for my game. Cheers!

Have you updated to the new Rockstar Games launcher?