Perfect, that did it! I knew it had to be something simple. I just didn’t have the time to really dig into it more. Thank you!
I have expanded the label size in this JSFiddle to make the issue more visible. https://jsfiddle.net/87jf5m2c/4/
Its only when a new label is added to the chart that the problem appears. about 5-10% of the graph-able area is cut off until the data-point and corresponding label have traveled that 5-10% at which point the full size is restored. At low playback speeds its not too bad, but at quicker speeds its quite jarring. I also wanted to add that the area cut off is proportional to half the size of the label entering the graph.