Hi douglasfrombuckley,
Thanks for reaching out using Apple Support Communities. Here to help.
We understand you are having trouble getting certain tracks in your music library to upload to your iPhone.
Are you subscribed to Apple Music or iTunes Match? These services would be required for the matching to occur. If you are subscribed to one of these services, ensure you have Sync Library enabled on both devices.
Turn on Sync Library with Apple Music
From the above article, if not all tracks have uploaded right away, check back later, as this process can take time.
If songs are missing from your music library after you turn on Sync Library
You may also be able to obtain helpful information from the status information of the tracks that you are having trouble with. What is the cloud status of these tracks on your Mac? Take a look at the next article for more information.
Identify cloud status icons in your music library on your Mac or PC
Hope this helps! If we can clarify anything further, please let us know.