"Add New" pages overwrite previous post unless refreshed once

This is an odd one, and I’ve been unable to find any info on it.

Basically, all of my admin pages seem to load a cached version first – a refresh is needed to show the actual current state. For instance, “All Posts” will show only the first few I ever added, until I reload.

But it’s especially annoying on any “Add New” page, because it will attempt to overwrite the last post or page I published. I first noticed this after the first auto-save: The generated permalink was the same as the previous post I’d made. Sure enough, when I went ahead and published the post (even after editing the permalink to make it unique), it REPLACED the prior post.

If I let it autosave, then reload the page, it works fine.

So far I’ve tried disabling all profiles, switching themes, and re-installing WordPress. This problem remained. Does anyone have any suggestions of what might cause this? Even just a point in the right direction will be greatly appreciated.

Thanks!