The rest of the story. The right one started to pass the test intermittently; the left one never did. Apple finally agreed to replace the left AirPods Pro. After repairing, the left passed the fit test, but the right one, which had been passing the test, failed. On a whim, I repaired the old, original left one and the right one started to pass the fit test. Replaced the old left with the new left and the right one started to fail the test. Apple replaced the right AirPods Pro and now both left and right pass the test. Not sure what's going on, but so far so good with the replacements. Thank you, Apple for the replacement AirPods Pros.