(Actually I'm using 2.8.5 not 2.8.4)
Got a strange problem that I've never had before.
I have a custom field. When I create a new post, I add the title, content etc. and then choose my custom field, assign it's value and update it. At this point, I am taken to a new, blank post editor. The top banner says "Custom Field Updated".
I can navigate to Edit Posts where it has saved a draft. Editing this draft, everything behaves as expected.
It's hardly a disaster but the client will possibly run into difficulty with such a quirk. Any ideas on what is happening?