Energy dashboard - wrong price calculation

Hi guys,
I´ve just purchased the Shelly 3EM device and connected it to the Home Assistant.
The entity itself is working properly and fine, but I have few problems:

As I am measuring 3 phases and I need to calculate all 3 phases together, I created a helper (sum of devices) - which calculates all 3 phases as a sum AND a template like this:

  - sensor:
      - name: "Kotel"
        unique_id: kotel_energy_total
        state: >-
            [ states('sensor.shelly_celkova_spotreba'), 
            ] | map('float') | sum
        availability: >-
            [ states('sensor.shelly_celkova_spotreba'), 
            ] | map('is_number') | min
        unit_of_measurement: kWh
        device_class: energy
        state_class: total_increasing

The problem is, that when I add the entity (the helper), it shows me correct data.
Total measurement for all 3 phases together.
For example now I have 134,33 kWh.

When I look at the energy dashboard, there is a different number.
At the same time as above, it shows 130,99 kWh.
And - I selected the fixed price - 2,43 CZK / 1 kWh.
And the energy panel shows me 111,68 CZK.
This of course is not 2,43 * 130,99.
It should show 318,3057 CZK.

I have waited till the second day that maybe the prices will be fixed by itself, but no success.

Can anyone guide me, what could be the problem?