No problems here for me, but a couple of days ago I did get what you described, where you click 'Submit Reply' and the button 'greys out' but nothing seems to 'happen'. The post did get submitted though, as within a couple of seconds, I'd already received a notification of a 'reaction' to that post - though it looked as it hadn't.   So if anyone gets that happen, just navigate to another page, you'll probably find the post has gone through.