"Premiere has been blocked from accessing Graphics hardware"

This is the message I get when I try to export using CUDA (GPU acceleration). When I try to export, it gets stuck at 0% encoding and won't continue. If I cancel, the viewport goes black and I have to restart the program.

I'm using Windows 10 with two NVIDIA GTX 970s and one 1070.

Here's a list of fixes I've tried:

• Switching to "software only" for rendering (works but I need GPU acceleration for the project)
• Clearing the media cache files
• Restarted my computer
• Ran Premiere as administrator
• Reinstalled Premiere
• Set Premiere to be high performance in the Windows graphics settings

I can't update the NVIDIA drivers, Premiere, or Windows as I'm using the latest versions of all of these. Windows is blocking Premiere from accessing GPU for some reason but I'm not sure how to fix it. Any information is helpful.