previews for lots of songs returning null

[lhendo]

I am using the api to grab songs previews and play them. This is working perfect for some songs however a large portion of songs return null preview urls (even though i know they have one as one plays when using spotify mobile without premium). I have seen suggestions about markets and this has not fixed the issue aparently. It seems to only be "popular" songs/artists for example all of Taylor Swift, Drake, Shawn Mendes etc cant be played a well as new Ed Sheeren songs (the older ones work fine).