Date Including Hours Magically

I've got a simple question and I'm hoping you all can once again help me out. I've been replicating a report from 2016 for 2017. New dataset, I'm the new owner and I've had great success. There is one item however that I just can't seem to figure out. 

I've got a number of tabs in my Excel file (2017 Delivery, 2016 Delivery, Geo Data, 2017 Delivery by Section, etc) and I've created a DATE tab so I could link everything with a relationship. My date tab is a straight forwad column with dates from 1/1/2015 - 12/31/2019 which I created using FILL SERIES in Excel. In Excel they are 'DATE TYPE' as well as in PowerBI Tables editor I've set every date field in every table to the correct format (mm/dd/yyyy). 

Now when I create a stacked column chart it's magically creating hourly data. I've got:

January 1, 12am

January 1, 3am

January 1, 6am

January 1, 9am

January 1, 12pm

January 1, 3pm

January 1, 6pm

January 1, 9pm

Now I've only got 2 days worth of data for this year so I expected the graphs to look different however I'm lost as to why and where the 3 hour segmentation of my date data has come from. Here are the screenshots of 2016 (former collegue) and 2017 (with magical 3 hour segments).

Any help would be greatly appreciated.