@Kathy,
You point to a second possible problem with your data (thanks for reminding me) - The RMS voltage displayed is computed using a base frequency, which in the US is a range around 60Hz. Are your seeing your Power Meter drop out in the same regions the Power Quality graphs drop out ?
If no, then I suspect that the dashboard rendering for Power Quality is less robust than the Power Meter. It either coughs up on missing data or on voltage frequency out of range.
I’ll continue to make the case for you to try Home Assistant with the Sense Integration or write your only little home-brewed Python to sample the Sense Signals data if you want to sort things out and get better data on what’s going on. More on writing your own home-brewed code below.