Thank you for supplying that support code - it appears that you are using a custom theme that was not designed by AllProWebTools. The theme name is "BlueZenithTheme".
It would appear that there is an error in the CSS file of this theme that is causing the state field issue that you are referring to. You can view the state field in the following AllProWebTools approved themes here (click the menubar item that says "signup" to see the state dropdown):
You will also find a working version of the state dropdown in our demo here: https://demo.allprowebtools.com/secure-create-buyer.php
AllProWebTools guarantees full compatibility for the themes found from our repository of free themes here: http://allprowebtoolsthemes.com
- we cannot be responsible for 3rd party themes. You can either contact the 3rd party theme developer for assistance, or use one of our free themes found at: http://allprowebtoolsthemes.com
I do agree that if you have been using the "BlueZenithTheme" with several of your clients, any defects in that theme will be found on all of the websites where that theme was used.