Cannot access power plans via WMI

I am trying to enumerate Windows power plans through very straightforward code that has been working for several years. On my Windows 10 64-bit machine, however, I am getting errors when I try to enumerate a collection of power plans.

I realize Visual Foxpro code is like a fossil, but it is still pretty easy to read:

loSchemes = CREATEOBJECT("Collection")  
loWMIService = GETOBJECT("winmgmts:\\.\root\cimv2\power")
loItems = loWMIService.ExecQuery("SELECT * FROM Win32_PowerPlan")
FOR EACH loItem IN loItems
    loSchemes.Add(loItem)
ENDFOR

The code has been working for years, from Windows XP up through (I think, anyway), Windows 10.

The error happens after loItems is instantiated via the ExecQuery() method call. The object exists and has visible properties, but if I try to access anything in the debugger, it says the expression cannot be evaluated. If I wrap the iterating FOR loop in a TRY..CATCH, the error I get is:

OLE error code 0x80070668: Only administrators have permission to add, remove, or configure server software during a Terminal services remote session. If you want to install or configure software on the server, contact your network administrator.

So, it looks like I am being locked out from power plan information because the process thinks I am remotely trying to change the configuration even though I am accessing WMI data from the local machine (where I do have administrator rights, incidentally).

I downloaded a "WMI Explorer" tool from Code Plex, and I actually get the same problem there when I try to iterate over Win32_PowerPlan. The log returns an error:

Failed to enumerate instances from Win32_PowerPlan. ERROR:

(That is the literal response -- no actual error is listed.)

This makes me think this isn't just some sort of Foxpro issue.

Edit

I downloaded a WMI process explorer from Sapien, and it displays a UAC prompt every time it starts, running it with elevated privileges. Both the 32-bit and 64-bit versions of that software can query Win32_PowerPlan and display results. I then ran the Code Plex WMI Explorer as administrator and it was also able to iterate over Win32_PowerPlan without errors. So, the issue appears to be unrelated to "bit"-ness and has everything to do with WMI data access requiring administrator privileges even though I am running locally using a login that does, in fact, have administrator privileges. Needless to say, I am still stumped... For the record, I can still access all sorts of other information via WMI: processor info, memory usage, processes, services, IP Address, and OS description. All of those modules still work perfectly. But when it comes to the \root\cimv2\power namespace and accessing power plans, no joy.

Further edit

Some other questions mention ImpersonationLevel, saying I might need to explicitly set the level to "impersonate" (an enumeration constant = 3). I am playing with my WMIService object and can read and write the impersonation level, but it is 3 by default. I raised it to 4 ("delegate") and still cannot access the power plan items. The query runs fine, but an error gets thrown when I try to access any properties of loItems. If I reduce the impersonation level to 1 ("anonymous"), then an "Access denied" error gets thrown on the ExecQuery() call. Finally, level 2 ("identify") allows the query and I can access the Count property without an error being thrown. But zero items are returned where there should be 5. I am confused now more than ever.

In summary, I cannot access power plan information from my local machine, even though I have administrator privileges, regardless. This is on a Windows 10 Professional 64-bit installation (all updates up-to-date), definitely no Terminal Server software installed.