X-Axis and data on chart change with categorical type

Dear all BI users,

Below is a problem I experieced while I using chart on Power BI desktop.

Hope you to share your wisdom to solve this error.

Condition

1. Set a chart
2. With [date] on X-axis, [Merchant] on Legend, [Sales Amount] on Value
3. Hope to compare the Sales Amount of Merchant by every day and month

Problem

1. At first it shows right data (like selected chart of Figure 1 on below)
2. After a drill up to month and drill down to day view
3. It shows not all days on x-axis and the data is wrong neighter (like selected chart of figure 2 on below) 
4. No other things done while all above 3 steps

Figure 1. At firstFigure 2. After drill up and down

Sincerely yours,

Lee, Hong Gwoo