Why the waveform signal does not intersect at the mid-section when the time/division scale is below 10ns in the KMM/BenchVue software for U2701/2A?

This is due to the hardware limitation of U2701/2A. The hardware is using a digital trigger, when the time/division scale is below 10ns, the points to plot the graph is not enough. This causes the graph to be unstable and slightly offset from the mid-section when trying to construct the best fit line below 10ns time/division.