ProgramFilesFolder64 not returning value as expected with Wow64 plugin

Since
g_ProgramFiles64Folder = SessionVar.Expand("%ProgramFilesFolder64%");

returns the x86 PFF, I would expect the following would get the correct PFF value on a 64 bit machine:
Wow64.DisableFsRedirection();
g_ProgramFiles64Folder = SessionVar.Expand("%ProgramFilesFolder64%");
Wow64.RevertFsRedirection();
iManageLog("PFF is: " .. g_ProgramFiles64Folder .. "\r\n");

but I still see:
[08/26/2020 10:55:13] PFF is: C:\Program Files (x86)

any help on what is being done incorrectly?