When opening the filter menu, there is presently no way to either import a filter from an existing file in the filter folder or by copy-pasting from clipboard.
You cannot either create a custom loot filter as the menus are unresponsive.
Finally, you cannot even close the filter menu window which prevents you from opening the main option menu. Thus the only solution that’s working to get out of there is to press alt-f4, restart the game and no open this menu anymore…