"Hidden albums" that are not displayed on the artist's page?

So... I was looking for an Earth, Wind & Fire album (the best of Earth, Wind & Fire Vol.1) I used to hear on LP when I was young (Even if I could find the specific songs and make a playlist, I wanted the specific album for both the songs and the order).

I searched for the artist, and looked for the cover on the artist's page. The album was nowhere to be found (looked on albums, compilations, live albums, etc. Looked in all categories, even if it was not the right category). No biggie, apple music does not have that particular album, right? Except I found it by doing a direct search by name half a minute later.

I would understand if its "hidden" because it is a "best of" album, but that is what the "compilation" category is for, is it not? Now I'm feeling kinda paranoid about Apple music having whole albums that are not shown unless you specifically search by name.

TL;DNR: I found an album that is not listed on the artist's page.

Is this a thing? or is this a weird coincidence? (for all I know it is something that only happened to me? Has anyone else found one of these albums, or maybe an "unlisted" song for other artists?