Sounds really similar to what I was seeing, the Material components were not found by the latest instabug library that pushed 2 days ago, because it uses android support library 23.1.1.
I went into Android Studio and made sure in gradle that my app compiled with using 23 (instead of 22 as before), but that also lead me to find that I didn’t have the proper 23 build tools, or the support libraries installed. I used Android Studio to get those properly installed, then I was able to roll in the latest instabug, that was calling for Material.widget.button and failing.