Hi ziko,
Thanks for checking this out. The problem also occurs (at least in simulator mode) with the 2000 and 5000 series also.
Would you please contact me when the problem is resolved?
Thanks!

3204, Example sent to you is in simulator mode, but also occurs with the hardware.

The RMS value 565.7 mv is correct for the entire waveform, and should be less between cursors because the waveform between cursors is never more tha 400 mv.