Indeed, the problem pointed out is the same as that link.
The theme simpre are two hours, so I suspect that your program by using the filter NOT include weekends, counting the days of 23 hours instead of 24, which then falls short filter and fill the sails missing with flat prices.
This adjusted to the time zone GMT + 1.
However Ralf says his tests with UTC + 1 and the flat bars are only 1 hour 🙁
In short, the program has weekends shorter than those measured with Swiss watches. Prefer these weekends ;-D