Sidney Toolbox custom posts show 404 error after update

I’ve been asked to look at a website, which is using the Sydney theme (updated to v1.60), Sydney Toolbox (v1.09), and the Site Origin page builder. I’m helping them gradually move across to Elementor, but in the meantime…

Since recent updates, none of Sydney Toolbox’s custom posts can be viewed. They still exist, and can be read in edit mode, but when trying to access them publicly (there’re published), all URLs show the 404 page. They mostly use the employee category, with posts shown on a carousel using the “Sydney FP: Employees” widget. The widget still shows each page’s image and employee name, but the posts themselves can’t be accessed.

I’ve tried disabling and re-enabling the plugin, clearing the shared server’s cache, and disabling Elementor in case there’s a clash. What would you suggest next?

If I uninstall and re-install the plugin, will they lose their custom post content?

Many thanks,
Simon