We can work around it by going to another page, logging in, and then using Asset Finder to navigate to this page. That keeps the editors’ login and so then gives them the correct permissions.
I’ve checked all the permission settings, can’t see anything different on this page. Does this sound like a bug to you?
Could potentially be a bug in that version, but might be implementation related as well. I’d suggest you contact Squiz Support for someone to login to your Admin backend and have a closer look there at the implementation and configuration of your Edit+.