XY Chart Line Not Displaying Correctly

I created an XY chart to display data with a line, and the data looked great for a while. Suddenly the line started looking really odd, and I don’t know if I changed something that may have caused this.

However, if I switch the exact same chart to use columns, the chart looks fine.

Any idea what is happening?

What does the dataset for the chart look like?

It’s a JSON dataset with 2 columns. One of the columns is a number (the height of the bars), and the other column is a timestamp (sorted from left to right). The only change I made between those two screen shots was changing the chart from a line to a bar.