No longer able to AirPlay from iTunes to Homepod directly I want to AirPlay music from Mac iTunes to HomePod. However, when I select it on iTunes AirPlay menu, I get "Sign in to Apple Music to play songs on your HomePod" prompt with Cancel/Sign in buttons. If I sign in, nothing happens and I get the same prompt on the next attempt. 

How do I get this to work? I do not have Apple Music nor iTunes Match subscription and I don't think I need one for this.

If I choose AirPlay for the whole Mac instead of iTunes, it works. But I would like to AirPlay iTunes only instead.

What makes it even more interesting that my desired setup worked for the first few days after setting up HomePod and then stopped.
Since you're saying this used to work the way you want it to, then perhaps resetting the HomePod back to its default settings will do the trick.

To fully reset it, follow these steps:


Unplug the HomePod
Wait at least five seconds and then plug it back in
Wait at least another five seconds
Press and hold the top of the HomePod with your finger
Keep your finger there even after the spinning light turns red
Continue to keep your finger there even after Siri announces that HomePod is about to reset
Finally you will hear three beeps to indicate that your HomePod has been reset
You can now take your finger off


Once your HomePod is reset you will need to set it up again from scratch.