I have the same problems.
When I first edit an existent post it shows the usual editing page, but no contents under the visual tab (not quick post), as in this print screen
(Originally, there wasn't the autosave warning, but when I repeated the process to save the image sequence, it started showing.)
Then I switch to the HTML tab, and it shows the expected content, as in this print screen.
Then, when I return to the visual tab, it remains empty, but with a slight change in the toolbar, as you can see in this print screen.
Finally, without changing anything, when I click on "Posts", at the left vertical toolbar, to return to my post list, it shows a warning as if I had done changes to my post and was about to loosing them (which I didn't). You can see the warning in this print screen.
Also, before leaving the editing page, I click on the Preview button (not sure how it is exactly named in english, since my language is portuguese), the post preview shows ok.