I just noticed this on my mopub page...
Your access to Marketplace is currently being reviewed. You can enable your inventory and set minimum CPMs during this process; note that Marketplace will not serve ads until you have been approved. If you have questions, please contact .
I wonder do you see the same?
This could be the cause of the ads not showing.
I noticed that i didnt have all my details filled in in my account.
No payment details set up either.
I did that and sent them an email for approval.
Hoping that fixes it.