Do you get the following error when trying to open Notepad++ from the context menu:

ShellExecute failed (2): Is this command Correct?
“C:\Program Files (x86)\Notepad++\notepad++.exe” “File you are trying to open”

If so, I have the solution to your problem! Simply navigate to

C:\Program Files (x86)\Notepad++\

and then right click the notepad++.exe file. Click properties from the popup menu and then click on the compatibility tab. Once there, un-check run program as administrator, hit OK and you should be set!

I ran into this problem and this took care of it for me, I hope it fixes your problem too!