Siri for tvOS (and therefore also HomePod mini) incapable of searching for matched/uploaded music in library

The title says it all. I have an extensive Apple Music library that is about 20% composed of uploaded/matched songs. The rest of the library is added from Apple Music. On Apple TV (or HomePod mini which apparently uses tvOS as for its Siri internals), when I request a track, album, or playlist that is from my uploaded library, the response is "I can't find that on Apple Music."

I can even navigate on Apple TV to my music library and view the playlist or album in question, but Siri is incapable of finding it on ATV or HomePod mini.

The exact same track, album, or playlist is immediately discovered by Siri for iOS or iPadOS, which can then AirPlay to those devices. But the devices themselves are crippled by the version of Siri implemented.

This is a recent development since around iOS 14.x, best I can tell. Previously Siri on ATV or HomePod mini was able to search my library, but no longer.

I have logged many, many service tickets with Apple over this but have yet to receive an enlightening answer.