Apexcharts - Question about statistics, period / group_by, duration, func: max

I have utility meter helpers which counts up the monthly energy of some entities like this:

It seems that the utility meters resets 1 hour to early in March 24 so that the last day of march is already 0.0:

This results in this:

The understanding of my config below with the combination of statistics: period and group_by with func: max is that I will get the max value of each month bucket. But it seams not.

  series:
    - entity: sensor.strom_solar_gesamt_energie_m
      offset: "-1y"
      type: column
      statistics:
        type: state
        period: month
      group_by:
        duration: 1month
        func: max

I could repair (update) the statistics entry in the SQLight_DB for all of the helpers, but I would prefer to understand how to set up the card config in a way that solves the problem.

I tried dozens of combination but nothing solves the issue.