What's wrong with the Post Preview?

[#1]

When creating my post regarding the authentication error I thought I'd have a preview of it, on clicking the tab I got a jQuery busy gif in the top left of the view but no preview when this gif went away! So I clicked the Rich Text tab again and my text was gone! I thought it may have been a hiccup with me having an image attached but I have just tired it again with only "Blah, blah" as the message body and I still get no preview and my 'original' message in the Rich Text tab is missing when I return to it.

Is this just me? I am using Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:43.0) Gecko/20100101 Firefox/43.0.4 Waterfox/43.0.4

[#2]

https://community.plus.net/t5/Community-Site-Feedback/Priority-Forum-bugs-have-appeared/td-p/1324025... again. Always click Stay on Page until you've posted and you'll be ok.

Somebody has already suggested it might be a Javascript problem.