Some GRC files run with no errors but don't plot

I have a simple grc file that shows the difference in Interpolation and Decimation using the Rational Re-sampler blocks. The program runs once, a "Time Sink" shows the signals(once) and then stops plotting and the Frequency Sink does not show a frequency plot at all. I've had other programs that do similar things, runs but nothing shows, once and freezes or for a few cycles and stops. Any thoughts on causes and /or how to solve/debug it would be appreciated. I am running GRC 3.10.5.0 on a Windows 10 Enterprise 12th Gen i7 machine with 32GB RAM. I've attached the grc/py and plot files.

Thanks...Tom