Hello Josh,
I started investigating this issue. I used an old small project I had for this purpose (I used the new assemblies). I did try a few things but I was unable to reproduce any exception. If you can prepare a small project that reproduces this exception, please do open a support ticket and attach it so that we can look for solutions.
When using an implicit style, as you have shown in your code snippet, both the vertical and horizontal axes are affected. This is because both of the axes have a PanZoomBar inside, even though the pan zoom bar might not be visible. So if you want to target only one axis, you can place the implicit style in the axis' resources:
Note that the purpose of this two-way-binding is
not to set SelectionStart of the PanZoomBar, but only to notify the ViewModel what is the current value of the SelectionStart. This is because the chart internally sets and coerces the slider's values. If you need to control the zoom, you need to directly work with the Zoom property of the chart.
Greetings,
Petar Marchev
the Telerik team