Firefox not showing up in default apps

I tried getting into the old non metro default app page (run: C:\Windows\explorer.exe shell:::{17cd9488-1228-4b2f-88ce-4298e93e0966} -Microsoft.DefaultPrograms\pageDefaultProgram ) to set Firefox as default but it still didn't work.

https://streamable.com/px7bv

Skodd said:

https://i.imgur.com/Lm0iWWq.png

Any solution for that?

Reinstalling doesn't work and I've also tried theses two fixes :
Windows 10: Set any browser as default when it does not show up in Settings? - Super User
and
Windows 10: Set Firefox as default when it does not show up in Settings? - Super User

I've always found you need to go thru Firefox first, least the first time, and use the option there. It's in Settings>General inside the "hamburger" upper right of Firefox.

Link info from FF support: Make Firefox your default browser | Firefox Help

Skodd said:

The option open the "Default app" page in Settings.

Yes, I know. What I'm saying is do it first thru the Firefox option inside Firefox Options, in the browser. That option will take you to Default Apps, and hopefully show a choice for Firefox.

I'm looking at the way to do that with the registry.

Seem like Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\https\UserC hoice is changed. When I set it to Opera I have ProgId has OperaStable (gets it's name from HKCR but I don't see Firefox ) and a Hash value that I have no idea how it's calculated.

I took the existing name from the ftp association registry key Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\ftp\UserCho ice (ff is assigned to it) and copied the value to the same key but for http/https... didn't work (I suspect it's the hash value, when setting Edge as default for both http and https, they have the same ProgId but different Hash value.)....... https://i.imgur.com/uglxytH.png

Skodd said:

I tried getting into the old non metro default app page (run: C:\Windows\explorer.exe shell:::{17cd9488-1228-4b2f-88ce-4298e93e0966} -Microsoft.DefaultPrograms\pageDefaultProgram) to set Firefox as default but it still didn't work.

https://streamable.com/px7bv

This Explorer Shell command has a ")" at the end, it will not work, it goes to the Documents folder. Try mine instead. Set FF to all it can do.

C:\Windows\explorer.exe shell:::{17cd9488-1228-4b2f-88ce-4298e93e0966} -Microsoft.DefaultPrograms\pageDefaultProgram