Something is odd about all that. As @bbrip with Carlos Mena, I yesterday listened to an album with Bernarda Fink. By her I had a few albums in my library, but all being Main Albums. So, today I added the Concerto Köln production of Händel’s Giulio Cesare to my library. On the screenshot from the Home page it shows as the most recently added album:

Bernarda Fink is definitely credited on this album:
Now, going to Bernarda Fink’s artist page, on the ‘Overview’ tab I get her eight Main Albums in my library, but as has been observed by others, her appearance on the recently added Giulio Cesare-album doesn’t show up.
Now, on the Discography tab there’s a hint why this may be so:
The recently added album is clearly shown on the ‘With René Jacobs’ section, but it isn’t identified as being part of the library. On the Home page it is clearly shown as having been added to the library, but here, on Bernarda Fink’s Discography page, the album isn’t being identified as being part of my library. So, of course on the Overview tab it wouldn’t show up as an Appearance of hers…