I tried to use the Edit button on forums.galciv2.com and forums.impulsedriven.com. It doesn't work on either forum. I haven't tried anywhere else.
In both cases, the screen appears to reload and just go back to displaying the reply. After trying to use the Edit button on forums.impulsedriven.net three times on the same post, the Edit button disappeared, but I'm still logged in there. (This happened a few seconds ago).
(Edit - The problem appears to be limited to the edit button below the reply. The top post edit button works ok.)