SharePoint 2013: UserProfileApplicationNotAvailableException... ProfilePropertyCache does not have...

Problem

You've opened a SharePoint 2013 Management Shell as the farm setup user administrator account (eg. spAdmin). You are attempting to add, remove or get SPProfileLeader data.  You can get an instance of the service application proxy just fine; but when you try to perform a command against it, you experience the following error shown in the shell:

Get-SPProfileLeader : UserProfileApplicationNotAvailableException_Logging ::
UserProfileApplicationProxy.ApplicationProperties ProfilePropertyCache 
does not have 48c36bfc-c2de-4a8a-afd5-04885b11c9bb
At line:1 char:1
+ Get-SPProfileLeader -ProfileServiceApplicationProxy $upaProxy
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidData: (Microsoft.Offic...CmdletGetLeader:
SPCmdletGetLeader) [
   Get-SPProfileLeader], UserProfileApplicationNotAvailableException
    + FullyQualifiedErrorId : 
      Microsoft.Office.Server.UserProfiles.PowerShell.SPCmdletGetLeader

Solution

1. Login to a farm server (that hosts SharePoint Server) as the farm setup user administrator account.
2. Launch Central Administration as administrator.
3. Go: Application Management > Service Applications > Manage service applications.
4. Select (don't click on) your user profile service application.
5. Up above, on the Service Applications ribbon, click the Permissions button.
6. Add the farm setup administrator account.
7. Enable Full Control for this account.
8. Click OK.
9. Close out the shell that produced the error message and open a new one as Administrator.
10. Re-run your commands.

References

• People search relevance is not optimized when the Active Directory has errors in the manager reporting structure
• When setting the MySiteHostUrl I get a UserProfileApplicationNotAvailableException
• Get-SPServiceApplication
• Get-SPServiceApplicationProxy
• Get-SPProfileLeader

Notes

• Thanks to Network Steve's post and Bram de Jager's post (referenced above) for providing the clues needed to solve this issue.  Steve suggested running the shell and commands under the farm service account to solve the problem I was experiencing.  This hinted at a permissions issue.  Bram's post was completely unrelated to the issue I was experiencing, but reminded me about how accounts are granted access to the User Profile service application.  Integrating the two discussions produced the necessary solution.
• Traditional SharePoint Server 2013 farm; hosted on Windows Server 2012 VMs.  Hyper-V.  Patched through April 2014 CU.