Save Draft doesn't save changes

Something changed in the past several days and now all my WordPress sites on the server have the same symptom. When I enter text then click Save Draft the post gets saved. But then when I change the title or text in the post and click Save Draft again, the new text isn’t there.

When I go to the list of posts and reselect it, sometimes the new text is there and sometimes its not. I’m at a loss. I’ve tried it with different versions of WP with the same results. Because it is affecting multiple sites and I’m not running multi-site I think it must somehow be related to the server but I don’t have a clue how that could be the case.