Ineligible Music - an example
I have a small number of tunes that show as iCloud Status Ineligible for Apple Music library sync.
Most of them are duplicates in which one of the two shows as "Protected AAC audio file" and one shows as "Purchased AAC audio file" (iTunes Kind). If I try "Add to iCloud Music Library" status iCloud Status changes to Waiting then back to Ineligible. Many of the are pre 2009.
I read that:
A Purchased AAC file is what a Protected AAC file becomes when it's been upgraded to the iTunes Plus format. These files no longer have the DRM-based copy restrictions. All songs at the iTunes Store sold after April 2009 are in the DRM-free Purchased AAC audio file format.
Even after I delete the Protected AAC files, so there are no duplicates, the Purchased AAC files show as ineligible. If I 'upload to iCloud' I see "waiting" then ineligible.
PS. This question is similar to Ineligible songs - Apple Community but is more detailed.