I also am having problems with Action! and RDR2.
I'm running Action! through steam as I have a steam version.
My specs are i9900k CPU, two 2080 ti GPUs, 64 GB RAM clocked at 3200 Mhz and I'm running Windows 10 with the latest Nvidia drivers and Windows updates.
I have no problem with the Rockstar Launcher, but when the game is launched, and I hit F9 to start recording, I immediately get this:
Perhaps I need to install some C++ dependencies? I am not sure.
I have made sure that Action! is allowed through the Windows firewall, and I renamed my video capture directory to 'Action' to remove the '!' as some people have reported that the '!' can cause problems. I can capture other games with Action! no problem.