Even with the Kindle update and the Vizio set to automatically reorient the page. Nook rotates fine, but not Kindle. I thought it might be the little lock tat used to be on the bottom right of the page, but that's gone now.
Have you checked the system orient lock, pull up the system menu in the bottom right corner it should be on the list with wifi, bluetooth and the rest on the mini menu. There should be a check mark by auto rotate screen.
We had this problem as well. I contacted customer support for Amazon Kindle. They had me Un-register and then re-register again. This fixed the rotation problem. (Don't ask my why... I can only guess that they are detecting device version and associating it with the account.)
