Tab content ent only shows on backend

I recently noticed that the tab controls on several pages seem to have failed all at the same time. When I look at the page in the editor mode, the tabs work fine, but when viewed on the front end, the tab labels are present and clickable, but none of the tab content is shown.

If I create a new set of tabs (even on the same page as broken tabs), the new tabs work fine, but all of the existing tabs are broken. I don’t know exactly when the tabs broke, but am running Advanced Gutenberg 2.3.3 and the latest version of WordPress as well.

I haven’t tracked down exactly what is breaking, but can see from a page inspector that the tab content retains the CSS property from the style sheet of display:none. Apparently, some javascript is supposed to add display:block inline to the selected tab as inline CSS?

I can of course rebuild each of the tab sets, but since this occurs on 15 or more pages, each with 3 or more tabs, I really would prefer to find a fix to fix all of them at once.

Thanks for your help,
Robert

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