As explained, WP Helpers was deactivated, the errors disappeared, and the Theme Customizer returned to normal. Prior to that, the wheel just went round and round; the visual display was all coding and the Customizer menu was blank – there were no options available for selection. Unfortunately, I’m unable to provide any additional information as once root of the cause was found, Piklist and its dependent plugin “WP Helpers” was deleted. Sorry, I like testing plugins, however if it’s going to disruption my business website, it’s gone. Cheers!
