Can't upload any images anymore because of quote amounts

Hi Team,

We update to WP 3.6.

On our main website we can't upload images because of the Quote amount restriction, but that's not correct:

We use 825 MB of 1014MB:
http://content.screencast.com/users/tnxt/folders/Snagit/media/73f9dcf9-29cb-4f43-92ee-6b497ef99256/2013-08-25_09-56-53.png

How can we fix this?

It's only not working on our MAIN website of the entire network. On the other website in the network it's working fine.

Is it also possible to create levels in Pro site to get more space for a specific level?

Thank you in advance for your help.

Stijn