After migrating from TFS2013 to TFS2017 in the company I work for I had the same problem with Workstation.Current.GetLocalWorkspaceInfo.
What worked for me is a call to Workstation.EnsureUpdateWorkspaceInfoCache:
TfsTeamProjectCollection tpc = TfsTeamProjectCollectionFactory.GetTeamProjectCollection(new Uri("<your-tfs-uri-here>"));
VersionControlServer tfServer = tpc.GetService<VersionControlServer>();
Workstation.Current.EnsureUpdateWorkspaceInfoCache(tfServer, tfServer.AuthorizedUser);
I added the above code lines to the constructor of my TFS proxy class that uses GetLocalWorkspaceInfo.