Hi Chris,
Thank you for writing in, is the site in question is in https protocol? If so, please navigate to Settings > General and check the WordPress Address and Site Address If it is set to https as well.
Also, do a test for a plugin conflict. You can do this by deactivating all third-party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
Please clear all the site caches (plugin, server-side, CDN, and browser’s cache) too, to make sure that this is not a caching related issue.
Let us know how it goes,
Cheers!