Syncing downloaded mp3 from Desktop to iPhone

[Munzi]

Hi everyone,

I am having trouble syncing some files from my Desktop (Windows 7) to my Iphone 6s. It works for some mp3 files, such as the ones in the Windows sample library. However, I downloaded an mp3 from a random page on the internet and this one does not get synced. It doesn't seem to be a space issue.

Other things I noticed:

- The mp3 file in question displays a duration of 0:00 in Spotify Desktop. I can play it, however I cannot forward to a different point in the song

- I can add the song to a playlist and it will still play

- The song is shown in my iphone's playlist then, however it's greyed out and upon clicking on it a menu saying "this song has not been downloaded" appears.

Does anyone have any idea what the fix here might be?