Months with 0 transactions not showing in bar chart
I am trying to create a simple bar chart in Data Studio with the dimension 'month of the year' (date range of 12 months) and 'transactions' as statistic. In some months there were no transactions measured. I want to have Data Studio show the month in the bar chart with 0, but instead it does not show the month at all. How can I make sure all the months are shown in the chart even if there are no transactions measured.
Thanks in advance.