Surface Pro 4 stylus side button events not recognized

I have a surface pro 4 working with the wintab drivers overall. Inputs such as touch, pen press & release, pen pressure, and eraser press events work fine.

The one thing that doesn't seem to be firing any events is the side button on the stylus.

For testing, I am using Krita 3.0 and have tablet logging enabled. If there is any information you need, let me know. I am pretty technical, so should be able to assist with anything I can.