Fiddle won’t let me use jquery.canvasjs.min.js as a http external resource (from here: https://cdn.canvasjs.com/jquery.canvasjs.min.js) so I can’t replicate the issue with my fiddle.
HOWEVER – copy and pasting my code incl the data into your fiddle replicates the issue. http://jsfiddle.net/4bc9v3hd/14/
Note how the tooltip shows the full ISO datetime (I am trying to make it show only the date and time) and the legend shows on 01/01/1970 for all points.