My own mp3 no longer available in my country/region?

Hi guys!

I know this question has technically been asked before however mine is a unique circumstance.

I write my own music and I had completed a track, exported as an mp3 and added it to my itunes and iphone music library.

Now, I was able to play it for about 24 hours no issue on my iphone. Suddenly the next day and after connecting to my pc just to sync/charge, my song is now greyed out and when I tap it, it says the song is no longer available in my country/region.

I re-rendered my song and created a new mp3 file and it still is greying it out.

I also tried rebooting the phone, re-syncing and logging out and back in to my region (Australia)

I find this very odd, considering the song isn't on the itunes store/apple music yet and it was my own file. It also is fine playing on my pc.

I note another song is doing the same thing. It's my own mp3 file (not my own song though) and it has greyed it out for the same reason.

I'm unsure whether this is just a glitch with my phone or if it's a widespread issue.

Thanks in advance!

~Fern