UAG 2010 SP3 - OWA Exchange 2010 - Large attachments fail to open

We have a UAG 2010 SP3 server in front of Exchange 2010 CAS. On the UAG side we have disabled the component installation and activation for UAG within the session configuration. When users access OWA and open attachments it works fine up until a certain size of an attachment. Somewhere around 10MB we are unable to download externally from OWA. At that point when clicking on the attachment a "The page cannot be displayed" is received. 
Attachments of sizes larger than 10MB are able to be opened internally accessing the CAS directly. Under the Download/Upload configuration of the OWA application in UAG Identify by URL is checked for both (Uploads has Identify by size but Download is unchecked). 
Is there a limitation on UAG to OWA download size? Is there any other configuration that should be checked to alleviate this issue?