Incorrect calculation of order amounts and totals (ex. daily view)

Hi. We have the problem that the number and totals of the orders are not correct, e.g. in the daily view. Example: In the order overview (/admin/commerce/orders) for April 13 (see screenshot) we actually have 18 orders and a total order value of 795.54 euros. However, the daily view of the reports for April 13 shows a number of orders of 30 and a total value of 1,861.07 euros. What's wrong? How does the report come up with these numbers? I would be very grateful for ideas on this. Thanks

EDIT:
Just got it with regeneration Order reports it seems to do things correctly.
Don't get me wrong but does that mean you have to regenerate the reports every day to get the correct numbers?

Thanks!