Hi Frank, thanks for your input.
First, see for yourself:
(CSS Style currently set to "Chemistry".)
Yes, I've changed and saved settings a number of times - tried ALL the CSS styles for example. None of them changed the Maintenance page.
I manage the site in Firefox. Then I used Chrome to view the Maintenance page - it shows up, but without all the options as mentioned.
Don't know about script conflicts; I use a fairly standard set of plugins on a number of other websites and they all "get along". A plugin that comes to mind is one that supports PHP within pages and posts; but again, it works with other scripts (Google Analyticator, Form Builder, Mail Chimp, Shopping Cart...).
Any further input is much appreciated, Frank. Its a great plugin, if those options work...