Thanks for getting back to us, jakobjosf.
Do you receive any kind of error message when clicking on the greyed out songs? You could also try signing out and back into Media & Purchases on your iPhone and see if the songs are still showing as grey. By going into your iPhone Settings > Your Name > Media & Purchases > Sign Out and then sign back in with your Apple ID and test again. If this resolves it, you can also do the same process on your Mac by going to the Music app > Select Account in the menu bar > Sign Out.
If the songs still show as greyed out, you can recreate the playlists again since they are playing normally in Apple Music or you can reach out to Apple Support so they can look into it further with you. You can see your available support options at the link below.
Get Support
Take care.