Hi Jack,
Thank you for using Syncfusion products.
XlsIO library works properly in a standard WPF/WF/Web/MVC/SL application but not in Metro application. The data binding error in 4.5 framework has been fixed in our upcoming release, which will be out by this week. So far, there is no any announcement on this.
Please let us know if you need any clarification.
Regards,
Johnson