Windows 10: UAC prompts missing after installing TortoiseCVS

On a new Windows 10 Pro x64 machine I installed TortoiseCVS 1.12.5. 
After that, when trying to copy files into a system directory like 
C:\Program Files, instead of showing a UAC dialog, nothing happens. The 
file is not copied and no UAC dialog appears. After uninstalling 
TortoiseCVS it works again.

To confirm this, I tried it with both 1.12.5 and 1.12.6 RC1 in a virtual 
machine with a fresh installation of Windows 10 Pro x64 and different 
features selected during setup. The problem appears when any of the icon 
overlays is selected to be installed, on 1.12.5 and 1.12.6.

I have also used Sysinternals Autoruns to disable all TortoiseCVS shell 
extensions (except for the icon overlays), but still the same: no UAC 
dialog when trying to copy a file to a system directory.

Is there a solution available yet?

Florian

------------------------------------------------------------------------------