File type editor, clearing application fails to save

When I edit a filetype and clear an action on the first tab by editing the action and clearing the application text field, it does say " afterwards, which is fine and looks the same as if I'd used the delete button at the bottom, but when closing and reopening the editor for the file type, the action is there again.

I would expect the edited action to stay like it was shown, if I close the editor and reopen it, as it is for the delete button.

before editing:

after editing:

after closing and reopening: