NDI Test Patterns is not a good tool to use for this workflow test. It doesn't send a constant stream of video frames (it's just a still image), so for applications that are counting the incoming frames they will report them missing, but the reality is that they were never sent.

I wrote an application that is better designed for these kinds of tests, NDI Signal Generator.
https://kanelp7.wixsite.com/kanesworld/ndi-signal-generator