AstronomerDaz

Really?? That seems like a huge gap in functionality?

Why would I want to recreate a Gallery and not populate it with the images??

+1 for this!

Closing

Well, I found the issue.
The PHP Code plugin by Otto is the culprit – but handily he has written a guide on how not to use his plugin!!

Sorry – should say my site is on WP5.2.4, all plugins are up to date.
My local installation is WAMP 3.1.9, PHP 7.0.33, Apache 2.4.39

Still no permanent fix for this?

Correction – it works OK if I view the individual post, just not from the home page…

Off to investigate

OK thanks.
Actually, it works fine from the admin centre, just not in the live environment…