Only parts of Spotify playlists available / playable on new iPhone 8 Plus

[aemassman]

I have Spotify Premium on which I have a number of playlists that I originally imported from my iTunes / iTunes Match.  These imported tracks were mostly from my own CDs that I uploaded to iTunes, with only a very few tracks purchased from the iTunes store. 

Over the years, I have added songs found on Spotify to various of my koriginal playlists.  I have previously not had any problems playing these hybrid playlists on my PC running Windows, my iMac that replaced it and on my previous iPhone 6.  Since getting my new iPhone 8 Plus, I have not been able to see/play parts of my playlists on the mobile app, (apparently the songs from iTunes) even though I can see/play complete playlists on my iMac.  I have tried redownloading the playlists without success.  Any solutions?

[user-removed]

Hello, Help arrive!
If you are experiencing:
A. Grey title in Playlist
B. Cannot play mp3/m4a on iPhone

Please make sure the songs import into Spotify:
a. Not protected by DRM
b.In supported format (https://support.spotify.com/us/using_spotify/features/listen-to-local-files/)

Steps:
1.Make sure your computer and mobile devices (iPhone) in the same WiFi network.
2.Remove the playlist which you find the problem
3.Remove and re-add the "Local Sources" - Make sure all songs synced.
3.1 Reopen Spotify app (MAC) [in case if you added too many songs] [Recommend to do]
4.Make sure all the songs which added can be played in Spotify (Mac)
5.Make whole new playlists (Recommend using different name from preventing sync error)
6.On Mac, check all the songs in playlist whether they can be played or not.
7.Download playlist on your devices(iPhone)

Please let me know if you have any questions.