Admin bar gone AWOL

I have just started developing a new site at https://edd.host with a development site at https://edd.dev

My dev server is a Turnkey CentOs Linux WordPress Appliance running Apache2 on an Oracle VM Virtualbox, here in Scotland, and the production site is on its own NginX server and reasonably chunky Ubuntu 16.04 DigitalOcean VPS in New York.

I am using GP Premium and have an additional 4 plugins running. All the software is bang up to date and the latest versions.

For some reason ~ nothing obvious in the console ~ the admin bar isn't showing up on the web site, although it is there on the control panel and admin side throughout the site.

I have deactivated all plugins, cleared caches etc on both instances, but it makes no difference on either server.

I am at a loss what to try next. Any ideas?

Terence.