I'm using Safari to view the site on my Mac. (Please withhold all Mac vs. Win vs. Linux commentary!) And, when private browsing is turned on, I cannot see a preview of my posts. Additionally, when I click on answer your own question, a blank space is present where the answer box usually appears.
If I turn off Private Browsing, this is not an issue.
Additionally, I do not get any tag suggestions. (I've just noticed this as I was tagging the post)