Virtual power sensor (manual) and Home Assistant Energy-dashboard

[ergy78]

Hi, i have a manual power sensor for my water boiler. When switch is on, 2000W load is assumed. I then have an automation that starts at the night at 02.00 and stops at latest 07.00AM. For some reason, Energy-dashboard "Individual devices detail usage"-chart shows less than 2 kWh for the first hour between 02-03 AM, while it should show exactly 2 kWh. Energy_daily sensor created by Powercalc shows the value of 2 kWh for the first hour. Any ideas why Energy dashboard shows wrong?

Total used energy is correct, but it's devided wrong between the hours