Works for me.

 Also, I recommend disabling AdBlock.

Weird ... just started working again!

C'mon, what did you do? 

I had the same issue for a while, but now it works (writing this via quick reply)

I have the green tick on for adblock on this site (I see all ads) and i have issues with the reply box. But i didnt on this thread. Strange. 

... and I don't use AdBlock 

I sometimes see my cursor jump when inserting a paragraph break from the line below to the start of the first word in the post for some reason.