File Association issue

I am using Microsoft Dynamics AX as a Remote App, the file association used with the Dynamics client is .axc.
I have added a folder as an icon in TS Web Access which contains numerous .axc file for access to different AX environments.

The problem I have is that these AXC files do not show any association with a program when the folder is opened through TS Web Access. If I create the file association then it works fine. Yet when someone else logs in the file assocation is gone again for them. It's almost like its individual to profiles, but I didn't think this was supposed to be the case with file extensions?

When I log onto the server locally the file assocation is correct. Is there something in the registry that wipes this association for new users? Once the file association is made for a user, it stays. Problem is we restrict the programs users can run using GP and they are unable to run the 'Open With...' wizard, rightly so.

I have checked the file extension into the registry in HKCR\.axc and everything seems in order.

Any suggestions?