Glad you found the cause, and now have it sorted.

Odd. You can see if this below may restore "Run as administrator". Run as Administrator - Add or Remove from Context Menu in Windows 7

I'm not sure why the menu item is gone while using Test Mode.

Yeah, the W10 version uses a different method than the W7 version here. If you still have the remove REG for the W10 version, you can use it to...

It sounds like you may have added the original "Take Ownership" from some other site since the one from here worked for you. Do you remember...

Hello Jez2k, :-) The "Take Ownership" context menu added by this tutorial will not get added to executable files and their shortcuts so they can...