When trying to open Workspace, the following exception is thrown:
[PolicyException: Required permissions cannot be acquired.]
System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission).
The issue was that SharePoint was installed on the same web site, then removed but the web.config was left in the root of the site (C:Inetpubwwwroot). This forced the site's trust level (along with all child sites) to WSS_Minimal. We removed the stray web.config and Workspace was able to load.