Why is my iPhone showing music as Unknown Album?

All my music on iTunes is sorted by album and has the album artwork attached etc, but when I last synced my iPhone, some music has come up as unknown album. It still has the artwork attached and all the albums names are correct in iTunes, so I have no idea why its only just started doing it? I haven't changed anything except made a new playlist, and some of the songs in the new playlist are ignoring the album they are in it seems.

Added (1). That makes sense, but its only just started doing it, I've had these song in my iTunes for a year and its only just started doing it.

Because you did not install the songs from an official album. If the songs were downloaded via converted MP3 source or via phone then it will show as unknown album. However for example if you got K Koke pure volum 2 album and installed the songs via that album to your phone or computer to you phone it will not show as unknown album, it will show "Pure Koke volume 2" Same woth any other album. Hope this helped

I had this same problem out of nowhere, or so I thought. Some music was sorted as 'unkown album' whilst others was sorted as normal. I then realised it was strangely alphabetical (up to ". " it was, with some exeptions, ok. After ". " I got this "unkown album" thing and at the end of the alphabeth it was ok again). I was, whilst synching my phone, updating the phone (which was a bad idea). So I just re-ticked the artists that where affected on my iTunes. I then updated the phone afterwards, restarted it and it worked wonders. There were some few artists still strangely put into "unkown album". These I renamed on iTunes (with the same name, mind-you). Now everything's in order again. Maybe this helps you? Probably not though because to me it seems clear that it was out of my idiotic idea to do updating & syncing at the same time.