If you want get month statistic working properly, you must set the shifts' time correctly.
You must use Shift Editor for set up shift's time. You can run this editor, for example, by long click on calendar cell and choosing "Edit shift" from context menu.
The shift time settings are in the bottom of the editor's window. First, you must set shift's start time and shift's end time. It is enough if you want the app calculate time of shift automatically. But if you have break up time that needn't to include to the statistic, or for example your shift includes different kind of hours like day | afternoon | night hours, you must do a bit more work.
There is "Count As" preference item in the bottom of window. If you press on it, the list dialog will appear.
Here you can see different modes that the app can use to count your working hours. Look at them:
This day. This mode used as automatic mode, shift time is a difference between end shift time and begin shift time. The shift will be added to statistic in the day when the shift is started.
Next day. Like "This day" but the shift will be added to statistic in the day after the shift is started. For example, if your shift start tonight, it will be calculeated as tomorrow shift (it is important in the beign and in the end of month).
Manual This Day. This is manual mode. The total shift time is the sum of fields "Day time", "Afternoon time", and "Nigth time". You can use these fields if you get different rent for every type of hours. Use this settins also if you want set shift time that is different from actual shift duration (for example, because of your lunch time). As in firts "This Day" mode, the shift will be counted in the day when it begins.
Manual Next Day. This is line previous mode, but shift time will be counted like tomorrow shift (look "Next Day" mode).
Split Shift. This mode allows you count your shift time in case when you shift begins in one day and ends in another. The hours before midnight will be counted for this day, and rest of time for tomorrow day.
On this picture you can see an example how you can set up the shift. The shfit starts at 3 p.m. and ends at 11 p.m. Also there is a lunch 30-minutes lunch time. They count your working hours as follow:
The picture presents the swing (afternoon) shfit. So, you have only 3 day hours, 3 hours and 30 minutes afernoon hours (do you remember about lunch time?) and 1 night hour.
If you have any questions, you can ask me by email or on any social network or forum what you can find in Feedback section of the site.