[ssbtech]

Sorry, I don't see an iTunes forum anywhere...

iTunes behavior is a bit odd. I only have one playlist that I sync to my phone, yet "Songs" under Library on my phone seems to show a massively long list of songs that I haven't sync'd. Most are indicated by a "Download cloud" icon.

Anyway, I was trying to sync the playlist that I sync. I had added a couple of songs, but they wouldn't show up on the phone's playlist.

i duplicated the playlist in iTunes, marked it for syncing and tried again - still wouldn't work. I deleted both playlists from the phone, and they then both removed themselves from iTunes. Not sure why the phone is deleting playlists from the PC, but there you go. I was able to restore the duplicate playlist by Edit -> Undo Delete Playlist, but not the playlist I had duplicated.

This ended up syncing fine.

[doogald]

If you have iTunes Music Library (aka Music Match), the phone will show songs that you have purchased from iTunes but haven't synced to the phone with a cloud icon, or even songs that you have in iTunes that you uploaded to iTunes Music Library but don't sync to the phone (the same is true if you are an Apple Music subscriber.). There are a few things that you can do - turn off iTunes Music Library (and Apple Music) in the Music app settings. Also, there is a category "downloaded music" that shows on the main screen of the Music app - you can just select that, and then see songs, playlists, artists, etc., that are actually on the phone.

As for deleting playlists, you are syncing the phone to iTunes. If you delete a playlists in iTunes, that deletion syncs to the phone (or iPad), but deleting a playlist on the phone also syncs back to iTunes. If you don't want a playlist on the phone, the proper way is to change the sync setting in the iTunes app. (See https://support.apple.com/en-us/HT201253 - turn off the settings "sync entire library" under music and change it to the playlists/artists/etc. that you want to sync.)