From the qobuz menu:
Search for “Thomas de Hartmann” then choose composer. I get 2 ‘main’ main recordings.
Qobuz lists 23.
It seems as if more are found but they are not displayed under “Main”.
If I click under “focus” → “Composed by” then they are listed.
But i already searched by composer. It seems the issue is that under “Main” the wanted search results are not displayed and you have to dig into a confusing sub-menu to get what you want.
I think the results are correct. When you click on the Composer link from a search, you are taken to the Overview page, and from there the Discography shows three releases in TIDAL. This is where he is listed as an ARTIST.
In contrast, the Compositions tab shows his works and the albums where he is the COMPOSER.
In Roon composer and artist are not equivalent. In my view, this is correct. Hartmann did not release any albums, and couldn’t have done so in 1979!
If you scroll down past the main section, you will see several other sections, including a “composed by” section. You may find scrolling more intuitive than leaving the screen and clicking around. It’s a shame that the screen is not configurable (which sections and in what order they are displayed).