This is definitely a bug. The crosshair remains displayed, but the crosshair label is hidden. In other words, it is snapping to the last data point but not displaying the value in the crosshair label.

If you can’t replicate it, try making the chart wider. Here is another example that may make it easier to see: https://jsfiddle.net/01dtnkme/. Again, if you can’t see it, make it wider.