I'm having an issue with the page after you register. I have the "Custom Thank You Message" enabled under the "Message" tab for the event, but after I register, It's not displaying any message. It's just a blank page. I have version 2.6.4b.
Hello. My assumption is that you have configured the wrong message. There are two thank you messages... two in the main config and two custom messages for the event. One message is displayed after a Pay Later registration. Make sure you configure and enable the right message.