I have the same problem but as you can see, I figured out a way to do it through trial and error.
1. Go to the posting window at the bottom of the page, click the toggle editing mode button (upper left hand corner) so you are in the mode where the edit buttons are disabled.
2. THEN go to the post you want to quote and it will put the quote in the window. You can add your comments and post directly to the thread from there.
....OR....(if you need to use the edit buttons on your comments)
3. THEN, click the toggle button again and it puts you back in the window with the edit functions activated and you can proceed from there.
But don't ask me why this works, it just does, lol.
hey, hey, hey!....I am glad that this board is full of folks that are smarter than me....thanks