Andrew Nevins on "Switched theme back and forth, missing widgets"

We're using Altitude Pro from Studio Press. I was trying to figure out a problem so switched to TwentyFifteen. When I switched back one widget is gone., and not in inactive widgets.

Any ideas why?

Have you contacted StudioPress about this? We aren't given access to commercial themes so we can't debug this.

I have, haven't heard back yet. I thought I'd post it here too in case there are people who have had the same problem and it wasn't particular to the theme. But I can close this if you think it's out of place.