oneleaf, that looks perfect, but if same-named ("file-manager.desktop" etc) .desktop files or symlinks exist in
~/.local/share/desktop-defaults/
those home-pathed copies would take precedence.
You could recreate a correct set of symlinks in this home path, or delete the home-pathed broken symlinks
and allow your newly placed system-wide defaults (symlinks read from the items in /usr/share/desktop-defaults) to be used.

delete the folder ~/.local/share/desktop-defaults (the whole folder, not just the contents). and then try the"Preferred Applications" button in the control center again.

dolphin_oracle wrote:delete the folder ~/.local/share/desktop-defaults (the whole folder, not just the contents). and then try the"Preferred Applications" button in the control center again.

Thanks guys! Deleted the folder and we are back in business.