The gallery was working.
I added one photo via ftp (because the uploader via the admin section won’t work) and rescaned directory
The gallery was working with the added photo showing
I added 7 more photos via ftp and rescaned directory
The gallery disappeared from the page
The gallery shows in admin with all the pictures there..
No other actions: no upgrades, no shortcode changes.
Deactiivated and reactivated NextGen