Plugin showing old (non-existent) categories in taxonomies

Hi: On my site I used to have your plugin a very long time ago when I had some old categories, posts and pages. I think it was then called Show/Hide Widgets or similar name? I removed the plugin for several years, and have now re-installed it and activated it.

When I try to select such that a widget should show only in certain categories on my site, the plugin is showing all those old categories that are no longer existing on my site and it is not showing the categories that are there at present on my site. Same with pages and posts.

How can I fix this issue? Please help urgently.