Yes the OSS is most likely for the same thing. Your SCN post actually mentioned that this issue wasn't in the hosted system. Of course I had already started helping support look at I what I was led to believe was an SAP hosting issue. : ) my bad...
Support will not be able to fix the issue as the solution is in the deployment. The provider will have to fix the deployment as I suggested above. Probably not a bad idea going forward to include the third party info as well in any OSS message. I'm guessing the partner is fairly new to deployment of the sourcing application yes? Its a bit different than other SAP applications and has a few quirks when it comes to deployment. If everything goes smooth its fairly straight vforward. But if there are issues and you are forced to redo deployments have them ALWAYS undeploy the completely first. I have seen any number of properties get out of synch when this isn't done, APP_CONTEXT is only one of several this can happen to.
If need be we can discuss this with your 3rd party folks.