Listed item page goes to error page

We are going crazy. We added several listings, all show nice on home page, featured, on G-map etc. but clicking on any one, goes to “Error 404” page. I have 15+ directories, and never a problem. Used 1st time Crown Child theme. But every setting for all sites are identical set.
No changes made to any core function, using identical plugins on all directories, deactivated all, and same error problem.
any advise greatly appreciated. https://yellowdirectnetwork.com