AME 14.3 freezes during encoding

I've been working on Premiere Pro on Windows 10 project for weeks, but suddenly today things stopped working during the export step.

I've tried to export directly within Premier Pro and queue it to Media Encoder and neither work.

I had been exporting to H.264 format successfully dozens of times until today.

Some recent changes:

1) I moved the project files from a network drive (F) to my internal C drive

2) I installed a NVidia Geforce RTX 2060 Super video card

I've seen two types of things happen:

1) Sometimes, the system will start the export and then it will just hang midway with no error message or explanation, or

2) I'll get an error message:

Error compiling movie

Accelerated Renderer Error

Unable to produce frame.

...
Error code: -1609629690

I've tried working with my project that I've worked on for weeks and a new test project with two tracks.and get the same results.

I've uninstalled Premiere Pro and re-installed it.

I'm unclear what to try next.

Any suggestions would be much appreciated.