Apple Music

cowhide,

Just to verify, do you have a current subscription to Apple Music?

If so, are both your iPhone and Mac signed into the same Apple ID? Check your Apple ID device list to see where you're signed in

If not, are you able to manually sync the playlist from your Mac to your iPhone per the steps in this article? Sync content between your Mac and iPhone or iPad

Cheers.

Hello cowhide,

Thanks for reaching out through the Apple Support Communities about that playlist on your Mac not appearing on your iPhone.

Is the Sync Library option enabled on both your Mac and iPhone? Turn on Sync Library with Apple Music

If so, is your Mac all up-to-date? Update macOS on Mac

How about your iPhone? Update your iPhone, iPad, or iPod touch

Also, if you create a new playlist on your iPhone, does it then appear on your Mac?

Hopefully those details will help to further isolate and address this behavior.

Take care.