In my case I could see all editors when running a local version of the website.
When I login to the live (remotely hosted site), I could not see the same. I even imported the non-working live website locally, and all editors worked fine again. This however seem to work on a second computer in my house!!!
After playing around, I found my issue was to do with the AV I was running. The one I have has a firewall module with ‘stealth mode web browsing’ feature . If this feature is enabled, all editors in the remote wordpress stop working. With it disabled, all work just fine.
Try this and see how you get on.