May I ask if "My Favourites or Function keys" you mentioned is the relevant shortcut in Microsoft Edge?
In fact, I think the problem you are facing may be related to two points.
- The keyboard map has been changed (including custom keys)
- Some applications have dedicated custom key combinations
First, I noticed that you tried to restore the keyboard's original Settings. It's not clear if you tried the registry modification method.
Here's how:
Click "regedit" on the taskbar and open "Registry Editor"
Find the path:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Keyboard Layout
There is a key in this path called "Scancode Map" Please delete this key and restart your computer to see if you can customize the keyboard shortcut again.
Disclaimer: This is a non-Microsoft website. The page appears to be providing accurate and safe information. Watch out for ads on the site that may advertise products frequently classified as PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
On the second question, you can try a clean boot, running only the services that come with your system, and see if eliminating the interference from third-party software makes a difference.