Calc chart x-axis labels

I have a table containing data on my credit card. Left-most column is the
monthly statement dates, (oldest to newest, top to bottom) which are not
always the same. The next column to the right is the monthly balance. When I
create a Column Type chart from these two columns of data, I have the
balances as the Y data, and the dates as the X column labels. For the X
column labels, Calc always sets the dates to the first day of the month, not
the real (table) date.

I have checked the "Format Axis..." settings, and on the Numbers tab,
"Source Format" is checked. I think this means that it is supposed to set
the x-axis labels to the format of the cells in the table. But, this is not
happening. All of the x-axis labels are set to the first day of the month,
i.e. 01/01/14, instead of 01/24/14 (the date in the table).

I have tried all of the other chart types, none of them source the dates
correctly. Is this a bug, or am I missing something?