Didn't catch that specific one but Dugway's been on my radar for a while. A mate of mine does a lot of overlanding out in Utah and he's mentioned signal weirdness out that way more than once, not just mobile but actual handheld radio cutting out in areas where there's no obvious reason for it.
The thing that gets me is the timing. If it lines up with any of the test schedules people have been tracking, that's worth mapping out properly. Has anyone cross-referenced the blackout windows with flight activity logs from the area? There are a few sites that track unusual aircraft movements and sometimes the patterns are pretty telling.
Worth noting down exact dates and times if anyone experienced it firsthand. That kind of granular detail is what separates decent research from just speculation.