HomePods cannot access Apple Music Library after consolidating accounts

I also had this issue. I did all the other steps recommended by others i.e.

• Factory reseting HomePods.
• Removing the HomePods from the Home.app and re-adding them.
• Signing into and out of iCloud on the iPhone.
• Confirming that the HomePods are using the post merged "Primary" account.

Here is the final steps I did to finally get the HomePods to access the Apple Music service:

1. Open the Home.app on iPhone.
2. Press the "3 dots" button in the upper right of the Home.app and select "Home Settings".
3. Under "People" press on my name listed as the "Resident (Owner)".
4. On this account/profile screen there is a warning that states to the effect that the iPhone is using an account that the Home.app is not. Press the button on the dialog confirming you want to use the the account that the iPhone is using (which should match your merged Primary account).
5. After the warning is dismissed, the profile page still listed both my Primary and Old Media account so I exited and rebooted the iPhone.
6. After reboot, repeat steps 1 thru 3. The Profile showed the same warning but this time after pressing it after a minute the profile updated to only show the Primary merged account.
7. Under "Connected Media" I pressed "Apple Music". This showed a page that confirmed the account being used was my Merged Primary account and the "Use In Home" switch was toggled on.

After that my HomePods could play music from the Apple Music service instead of just my Purchased Music from my Personal Apple Music Library.

I've have this same problem. I was able to get it back by completely 1) Hard resetting HomePod, 2) Removing HomePod from Home.app and 3) re-add HomePod to Home.app. After a few minutes, they were able to play music from my library....until about 20 minutes later when I started getting the same "I couldn't find Billy Joel in your music library." All of my Music (including Billy Joel) appears in the Music app on my iPhone and MacBook Air. Everything is logged in as my primary Apple ID.

Additionally, after doing the Purchases migration, I lost all my Playlists going back to 2004. Gone. Apple customer support said that playlists only migrate if you have an Apple Music subscription, which I do not. Of course there was no warning of this when I did the migration.

Thanks for the reply. I confirmed that all my devices (iPhone, Mac, AppleTVs, Home.app, HomePods) are all logged in with my primary Apple account ID. My HomePods (when spoken to directly) cannot find anything in my Music Library, even after restarting my iPhone.

I have a case open with Apple and have already spoken to a senior engineer and they seem to be just as stumped. They see that my iTunes Match subscription is still associated with my old email account and say it should not be since I went through the migration. So they really can't say why Siri on the HomePods is the only device that cannot see my Music Library when all my other devices can. He said he was going to speak with the software engineers responsible for the migration process to see what needs to be done to fix it. He said he would call back today, so if I get a solution, I'll reply again.

I've had a case open with Apple Support for about two weeks now and it has escalated several times. They are able to confirm that my issue is that my iTunes Match subscription did not migrate (although it should have) and it is still under my old ID that I can not longer use after the migration. All of my music was purchased under my old ID. They haven't provided a solution yet, but maybe my issue is a bit more unique.

Just wanted to say that this finally worked for me. I thought I performed these steps before with no luck, but I tried it again today and it worked. Either that or Apple Support is playing with my account behind the scenes (I have a case open with them) and did something to make it work.

What finally did the job is under Home Settings, choosing my name "Resident (Owner") and logging back into my account. Previously I had a specific ID (the same primary Apple ID) selected under HomePods settings. I also did the reboot in between changing settings. Apple Support is supposed to call me back this afternoon, I'll let them know that following these steps in this post is what fixed it. Thanks!