Probably because the 4.7.1 installer still registers as just "4.7" in add/remove programs in CPL
So how do PatchMyPC users fix it?
I figured out how to fix it:
1. Open Regedit.msc
2. Paste
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\TreeSize Free_is1
into the line just below the "File Edit View ..." near the top of the window.
3. You will see 2 places with a 4.7 on the right part of the window. Change both places to 4.7.1 and it will not be flagged by PatchMyPc until a newer version is created.