Cannot show author and date on posts

I am using Mantra and very few plugins as yet. Author and Date were set to Hide in the Mantra custom settings. I changed to Show and got the following message:

“If this message remains visible after the page has loaded then there is a problem with your WordPress jQuery library. This can have several causes, including incompatible plugins . . .”

I deactivated all the plugins and uninstalled one that seemed dubious. Now the message does NOT stay visible, but still can’t get the Author and Date to show. Posts page: https://zivadogmedia.com/category/a-to-z/.

I am not a programmer but I’m not a complete nincompoop either. ??