Thanks for the file @fearguyq! After 30 min troubleshooting, I think I figured it out!
The culprit appears to be the shapekeys. It’s creating a discrepancy between the multires data and the base mesh. Which makes perfect sense in hindsight. To solve this:
- Go to your shapekey panel and create a new shape from mix.

- Next delete your previous 2 shapekeys with the “-” button, leaving your new shape from mix only. Then delete than one last. This process essentially “collapses” your shapekeys into a consistent base mesh.
- Next go to your multires modifer, change your viewport level to the highest (5) and click Apply Base in the “shape” section:

- At this point you should be able to bake cleanly with your viewport level at 2, render at 5.