Generate optimized media suddenly using almost entirely CPU

Exactly as the title says. For awhile, optimized media generation was making good use of my RTX3070 and completing quite fast. Now... it's barely using the GPU at 20% and takes 3-4x as long while CPU use is near maxed out. This was a totally sudden and random change (or maybe related to latest Resolve update)

Tried updating to latest Nvidia studio drivers.

Yes, this is Resolve Studio.
Yes, GPU is properly and manually selected.
Yes, CUDA is manually selected.
Yes, I've tried this multiple times to confirm it's 100% repeatable. The program is behaving more like the free version than the paid version.

Some codecs are CPU bound. What is the source and optimized codecs?

Exactly the same as they were before when it was using almost entirely GPU and completing in 25% of the time.

[Rohit Gupta]

What is your source clip format?