It has become evident recently that applications based on DirectX 9 such as the NestDrop music visualizer, can receive with only two compatible texture formats, BGRA (with alpha) and BGRX (alpha disregarded).
Importantly, the commonly used RGBA format is not compatible and results in black for the receiving application instead of the expected texture.
There can be other reasons for a black result and the most common one, particularly for laptops, is that sender and receiver are running on different graphics processors. This can be prevented by attention to matching Windows graphics performance preferences.
But in this case, the way to check is to open SpoutLink, right click to select the sender application and look for RGBA texture format (DXGI_FORMAT_R8G8B8A8_UNORM).
Now in the receiving application, you can select the sender named “SpoutLink” which is a direct copy of the original but with a compatible format and this should be successfully received. Again for course, make sure all applications are using the same graphics processor.