I assumed the EV miles stayed on zero for several minutes because of designed-in hysteresis, where Honda didn’t want to display EV miles until they reached a certain threshold.
I’ve used HV Charge about 6-8 times. Starting, in a few cases, with a depleted battery and a few others, with some charge remaining. Typically, just single digits as displayed on the EV range screen. Similar results, either way, using my seat of the pants methodology. In the cases where there was some remaining range, that range decreased ~3-5 miles while traveling ~3-5 miles after initiating HV Charge. Once the range started increasing, it did so in increments of .3 miles.
By comparison, when initiating HV, I have not noticed a drop in range as significant as when initiating HV Charge. There seems to be something going on that takes a few minutes before significant charging begins. Perhaps an engine warm up, an assessment of the battery and a low initial charge rate?
When initiating HV with 0 EV range, the range does indeed, pop up to ~2 miles after several minutes. For all I know, it could be dipping down to -2 miles before rebounding, but the display does not show negative numbers.
The power flow graphic will show electrons flowing from the generator to the battery but it will not tells us the quantity of electrons.