problem with payment for all users and sub sites

I am extremly concerned. The reason I chose marketpress as it allows all my customers to set up a online store with just a paypal email

but now I am getting this on the checkout and people are starting to mount up and moan at me

12203 - Instant payment required for 3pxo. - Instant Payment in 3PXO cannot be pending. The transaction has been rolled back.

https://premium.wpmudev.org/forums/topic/problem-paypal-express-checkout-sandbox-error-12203

similar problem here but I have no idea what the resolve was.

Also I noticed you now say only 10 sub sites can check out at once... is this all? also... where are the other global carts we used to have?