I have a master account and the three core books, one of my players has volos and sword coast, content share is on, I tried to create a goblin character as an NPC but I don't have the option too where as he does, is it I can look but not use it?

You'll have to create this character inside the the campaign I'm pretty sure. The sharing allows you to access the compendium content outside the campaign but for the character creator to be able to use the content you have to build a character inside the campaign.

To do this copy the link in the top left corner of the campaign and enter it in the url bar, then choose the option to create a new character, then you should be able to access this content

I also have the master sub. My players are able to view my owned books, but I'm currently not able to view the campaign one of my players bought in the compendium. Only direct links to items from that book.

Can you see in the compendium other things they bought, but you didn't?

Yeah that must be it, thanks guys

I've now lost the ability to even look in compendium, I have even cleared cache