In the initial state, it seems there is a case that does not work in Windows 8.1.
Resolve to apply the Windows Update 2955164
See: kb2953222
If you can not apply the Windows Update, it can be avoided by applying a touch to mouse mode.

It seems similar problem has occurred again in Windows 10 Anniversary Update.
2016/08/21 Currently, the information of the Windows Update fix is unknown. 2017/04/08 Fixed by Windows 10 Creatores Update!
It can be avoided by applying a touch to mouse mode.
Other way, it works by return to the previous build a Windows 10.

It can be resolved by editing the registry.
Please be careful editing of the registry.
Solution
1. Press the Start button.
2. Run registry editor by typing "regedit".
3. Display the following location.
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\TabletTip\1.7
4. Select the "Edit" -> "New" -> "DWORD (32bit) value"
5. The name of value : "EnableDesktopModeAutoInvoke"
　The data of value : 1
6. Restart Windows.
Or, there is no problem with the build of the previous Windows 10.

If GPU resource usage is high or the refresh rate is not keeping up with the GPU's resource usage, you may experience flickering windows.

This is a fundamental problem that cannot be eliminated due to the inherent problem with Windows DWM based window compositing.
For example, if you use an awful lot of windows in Notepad, you may experience flickering without zooming in. This should not be a problem for everyday use as it requires an extraordinary number of windows.
However, with TouchZoomDesktop, depending on your GPU's capabilities, the problem may be more pronounced.

How to mitigate it:
- To reduce GPU resource usage, reduce the number of window running at the same time. It may improve resource usage and lower the refresh rate.

- To reduce the refresh rate, increase the flicker reduction in the Anti-Alias settings page in the TouchZoom Desktop settings. (Reduce the refresh rate.)

- Lowering the screen resolution (number of pixels) may improve it.

When you have a problem with the standard Windows Magnifier tool's lens mode blacking out, it seems that the same problem can occur in TouchZoomDesktop. This seems to be an issue between Windows and the GPU drivers. According to Microsoft's Answers site, in the case of NVidia, some adjustments in the NVidia control panel may improve the problem. Or it may happen after some Windpws Update. In that case, there have been reports that a clean install of Windows fixed the problem.