We're talking it over internally now. Despite the lack of hardware I think we are basically reproducing the issue, though there is some debate over whether it was introduced yesterday (I trust you if that is the first you noticed it, since you were actually using widgets tied to this extension).
Can I ask if they've disappeared entirely from the dashboard, or if it is that they are just broken? I'd expect the latter.
If the widgets are still present but broken, could you screenshot the settings page for even one of the widgets tied to the MCP23017? That will reveal a lot (our widgets tend to lose dropdown menus when they break). I'd also be interested if you can even rename the widget and click 'Save' or not.