When using a sampleRate different than 1 in SignalPlot & SignalPlotConst the min and maxRenderIndex properties don't seem to behave properly anymore.
I tried to play with the sampleRate value to see if I could see a pattern that made sense (like min and max being double for a sampleRate of 2 or something) but I couldn't see anything...

Just try

plt.PlotSignalConst(ys, sampleRate: 2, minRenderIndex: 100, maxRenderIndex: 200);

and at least for me this doesn't work
(Using the latest Scottplot 4.0.42 with WPF)