There are probably a lot of similar questions, but none of the solutions work for me problems nor are the problems exactly mine.

So forgive me if this is "yet another one of them sync problems".

I'm trying to sync local files to my iPhone but for some reason certain songs won't sync, absolutely frustrating. I do see the songs appear in the list of songs on my iPhone, but they stay grayed out.

I've already done/checked:

• I'm on the same wifi as my iMac
• I have enough space on both my iPhone and my iMac
• I'm most certainly not over the 3333 limit on my iPhone or the 9999 global limit of local songs
• I'm still sane
• I've re-downloaded the entire list, but the same songs stay grayed out
• I've checked if the song is already on Spotify (one of the solutions mentioned that it may try to use the server-side song and that's why it could break), but the songs are not on Spotify
• I'm still sane
• I, yes I did it as a last resort, deleted the entire Spotify app on both devices (iMac and iPhone) and re-installed and re-downloaded everything. Still the same songs stay grayed out

By now I'm thinking maybe it's not Spotify but the song which is wrong, corrupt or something in between. But:

• iTunes, VLC and other media players are playing it just fine
• It is an mp3 file (2 audio channels, 44.100 sample rate...not sure of it matters but hey I'm still sane)

So I'm kinda lost now here. Whenever I have the app open on my iMac and iPhone and I delete/add songs to the list. I see the list updated on both ends, but it just won't sync.

Still sane.