Time Machine with Two monitors.

Hello. I have a current generation Macbook Pro and I use a USB Display Link to drive two monitors. When I go to enter Time Machine on my main monitor (the one with the menu bar and dock) it brings up the windows to go through, but the background is completely white instead of having the space and stars. I'm pretty sure it's due to the USB driven video on monitor one because if I switch monitor one to the Display Port, Time Machine appears normal. So I guess my question has two parts. 1: Any idea what causes this? 2: Is there any way to get Time Machine to open on my secondary monitor? Any help would be much appreciated. Thank you.