I've just upgraded to your newest version 2.6.3 and am glad to have the "Edit Related Posts" function back.
However, I can't get that function to work for me yet. When I'm on the post, I click "Edit Related Posts" and then I just get a blank screen, meaning nothing shows up under "Select Other Posts", so there is nothing I can drag to the top part of the screen.
By the way, I have at least a dozen posts so it's not an issue of not having any other posts available.
Any help to solve this would be appreciated.