I have not seen this before, but if you’re concerned about losing content and want to export, there are other options – you could try a plugin (there are many, I like wp-dbmanager), then backup your DB and download it first.
Anyone with Core or elsewhere have a reply that does not note to use a plugin which looks to be a core issue?
I was able to resolve this finally. I had at one point installed, activated, and set some roles with the Members plugin. We then decided it was not needed, so I deactivated it.
The fix was this:
1. Re-activate (reinstall and activate if necessary) the plugin.
2. There are two checkboxes in the settings page for this plugin. Uncheck them both, save settings. Upon doing so, I could then see the export menu item under tools and export.php worked as it should.
3. Deactivate and remove the plugin.
4. Never use it again as it not being actively maintained here, the dev, does not provide support here, which amazes me that WordPress is allowing so many to do so.
Plugins here should be supported and maintained here. Period.
