Hello William,
Thanks for writing to us.
I would suggest you please set the custom Header condition priority as 0 when your assign the custom Header layout to any specific page. Please have a look at the given screenshot below to learn more about how to set the custom Header conditions.

If you have not seen our condition and assignment doc, please have a look at it.
In case it is not working for you please purge all the cache and clear your browser cache then check it again. If it doesn’t work for you we need to check your settings. I would request you, please share your details in a secure note. Please provide the following details meanwhile you must troubleshoot a few common issues before we investigate your settings.
- WordPress Login URL
- Admin-level username and password
- Exact Header Name and specific page Name
You can find the Secure Note button at the bottom of your posts
Thanks