Yes, from what Apple Support (level 2) has told me either a current or past subscription to Apple Music or iTunes Match on your Primary account will make you non-eligible. The support person which I spoke with said his online notes were very clear on this point. As was the internal error message he was seeing for my migration attempts.
My take on this whole thing:
Remember, any music data on the Secondary account is going to be migrated into the Primary. I think this limitation was meant to prevent users from damaging their Primary account music collections. Some may remember the headlines from 2016:
Earlier this week, I wrote about the nightmare that is iTunes and Apple Music. My cri de coeur was prompted by a widely circulated blog post by a guy...
slate.com
It was almost two years ago that Apple announced it was acquiring Beats by Dr Dre, and by the end of August 2014, the acquisition was finalized. The most common rumors were that Apple was going to use a digital headphone jack instead of the traditional round analog headphone jack in all future...
lowendmac.com
Last week, a blog post by a designer named James Pinkstone made the rounds; in it, the writer claimed that Apple Music and iTunes teamed up to delete his 122GB of local music files and basically cause havoc with his library. This isn't the first time we've heard of oddness around how Apple Music...
www.yahoo.com
It was a different issue, but as of 2023 there were over 90 million active Apple Music subscribers, so Apple is probably not going to take any chances with this monster. By the way, that is one boat load of non-eligible accounts.
One other thing:
This is the statement in the Apple Support document for migration of account purchases that addresses all of this:
“You can’t migrate purchases if both the primary Apple Account and the secondary Apple Account have music library data associated with each of them.”
This is vague, there is no way that is an accident. What if you take out the words “music library data” and replace them with “Apple Music or iTunes Match subscription”. Most people will have their active subscriptions on a Primary account. Imagine if just 2% of those 90 million users tried cancelling their subscription for 90 days to see if they could get their Primary account clear of all music data thus making a migration possible.
Anyways, lots of questions and assumptions with very few answers.