Apologies @jillsdablog,
So it seems related to the latest WordPress update?
Could you please check for existing conflicts in your end?
1.- Temporarily deactivate all your plugins except NextGen Gallery.
2.- Is the problem solved? Then, it was caused by one of your plugins. Please check one by one and find the one causing the problem.
3.- If the problem is not solved with the deactivation of the plugins, try changing to a standard WordPress theme, it could be a conflict with your current theme.
Note: We recommend performing a full website backup before any troubleshooting.
Please, keep us posted, we are happy to help!