So, I just called GEICO to get some more information. My mother worked for an insurance agent when I was a kid, so I knew some of the lingo they'd probably throw at me, and I have a feeling that what they told me is probably 100% correct.
Basically, the Ascent is such a new vehicle that they don't have enough data to properly "rate" it yet. These are rating that generally come in over a period of time from multiple 3rd parties, and it takes time to gather that data and properly rate the vehicles. For example, the IIHS Safety Ratings were just published in the last couple of weeks. I imagine that could potentially affect the vehicle's rating.
What I'm guessing happened (and this is speculation on my part) is that, in the absence of all of the necessary data, each insurance company probably chooses a similar vehicle to base its information on. That would explain why
@Stubaru said "Auto-Owners had it as an Outback on my paperwork, they new it was wrong, but said as long as the VIN is correct thats all that matters.". Maybe Auto-Owners rated it similar to an Outback, while GEICO rated it similar to a higher-end vehicle? Who knows for sure.
Its entirely possible that within 6 months, GEICO's rate on the Ascent will come down, while everyone else's goes up. IN the meantime though... I think I'm switching to Progressive, which will save me about $300/year on my 2 cars.