This is a weird regression, and I don't see why it's technically required. The revision browser doesn't have much reason to be inline on the page, it could easily launch a new browser window.
Older plugin metaboxes can break this feature. That seems like the majority of plugins 😬
For Visual Revisions to work, every plugin on your site needs to use modern-style metaboxes.
@thegadgetmonkey I appreciate that after "is WordPress still safe?" you followed up with the good advice to update and have a good host. It's worth noting @WordPressVIP hosts some of the largest and most secure sites in the world, including NASA and the White House.
