Lightroom can't batch process AI denoise selection. It stops while about 1/10 of the way finished and never finishes. Once you cancel, it never lets you apply that denoise to them again. "Requested adjustment is not applicable."."

I selected 45 photos, all 46mp from my Nikon Z8,and batch applied Denoise. Completed without any problems. I do not use xmp sidecar files, so have auto save to xmp turned off.

What were the results for step 2?

I’ve restarted multiple times. It does nothing. I can’t find any xmp files in the photo folder.

To narrow down where the problem is and file an actionable bug report if necessary:

1. If you restart LR, does the problem go away, at least for a little bit?

2. Try removing one of the photos from the catalog for which you got that error. Look in the folder containing the photo and delete any accompanying .xmp sidecar.  Then reimport the photo and try to apply Denoise -- do you still get the error?