Hello,
I found that on my computer (MBP retina) using safari, sometimes I cannot chat because the box below the chat window has zero hight and I can’t click inside it.
Somebody on the chat helped me out. It turnes out that when I zoom out (e.g. using “Ctrl”+"-") the chat box appears again. Just wanted to report this such that other people experiencing the same issue may find this solution.
Gr. J.