Windows 8.1 introduces some "features" to accommodate mixing and matching high resolution displays with other displays. However, these new features may break SaT. If you are trying to include a site, and getting a "Button detected as black" message, or if tables are not going to the stack, then this could be an indication of these problems.
One way to know that you will have the problem, is when you drag a table between two different screens, if you see the table resize itself when you drag it to the other screen, then you will have an issue.
First thing to try is this: There is a setting you need to change in the Control Panel. You need to turn on this checkbox: "Let me choose one scaling level for all displays".
See this video (1m22s):
After you turn that setting on, you will notice that the size of everything on your desktop will have changed. You will want to tweak the scaling % setting to something comfortable for you. You may also need to adjust the brightness and such from the buttons on your monitor.
Finally, you should remove and re-Include all of your sites that you are having problems with and re-test. Also see if tables still resize themselves when you drag between different screens or not.
If that doesnt solve it, you might also need to disable this setting on all of your poker sites, and on SAT as well. Right click the shortcut icon for each poker site, choose Properties, then choose Compatibility tab.