downloading and syncing music from my computer to phone

When you subscribe to Apple Music your own local content should be scanned and either matched or uploaded to iCloud Music library. As long as you keep all of the content stored locally on your computer, and ideally backed up as well, then when you decide to turn off Apple Music you only lose the additional content you've obtained through the service. If, on the other hand, you delete local files to free up space, because everything is now in the cloud, and close the Apple Music service before redownloading your personal content then you are going to get unstuck. Assuming you still have your media I suspect you need to turn off iCloud Music Library on your iPhone so that it can clear the Apple Music list, then turn it on again to properly load the new version of iCloud Music Library made with iTunes Match.

See About iCloud Music Library icons and status - Apple Support to review the status of your library. Ideally everything will be purchased, matched or uploaded. You can select anything that says Waiting, right-click, and add to library, in order to try to force it to update.

tt2

I have this exact problem. I made the mistake of subscribing to Apple Music. When I unsubscribed I lost all of my ripped music. I had to re-subscribe to get it back. I called Apple Support and they assured me I could cancel Apple Music and still keep my ripped music. I unsubscribed and for awhile I did still have my stuff. Then it all went away on both my iPhone and MacBook. I just subscribed to iTunes Match and now the songs on my iPhone are giving me that error message. On my MacBook they appear to still be downloading but there isn't any way to check the progress and I haven't seen any progress in 48 hours. This shouldn't be this difficult. Whoever was in charge of this at Apple really screwed it up. Any help would be appreciated.

Do you have either Apple Music or iTunes Match?

tt2