Issue with updating stacked bar with date

Hi!

I have a stacked bar chart with time and duration in excel 2013 (i'm trying to show 30 day milestones). I had no problem the 1st time I created the file.

Now that I need to update the dates (to have my new future 30 day milestones) the chart does not update correctly: it extends the x-axis in the future but also in the past:

currently the file is from 7/15 to 8/15, when I put dates from 8/12 to 9/12, it extends the file from 5/26 to 9/23.
File is attached, thank you so much for your help