I'm not sure how to classify this issue type, so bug may not be correct.

I've run into a release where the release-level Mastering AR would not be correct. The "right" level would be at the Medium level, not at the recording or release levels. https://musicbrainz.org/release/3e55ca73-6b98-4b28-bf6b-b944a07e2f97 had mastering by Hal Diepold on CDs 1 and 2, and Eugene Thompson on CD 3. I could easily imagine a similar situation on one of the giant 100+ disc sets. There's no such thing (as far as I know) as a medium-level AR, however, which would leave the recording-level AR the only fully correct AR, given that the release-level AR would not be 100% correct for either Hal or Eugene here.