Here's a bit more explanation for everyone here.
The short answer is, the Steam release progress dashboard UI is confusing and misled us into thinking all release checklist items were approved and that the release would be automatic.
The long answer: apparently even when all UI indicators are marked as 'Approved for Release', your game is in fact, not yet fully approved for release. If the 'Mark as ready for review' button exists (it did), it means your game isn't fully approved (despite literally saying 'Approved for Release' in bright green at the top). In fact, we pressed the 'Mark as ready for review' button months ago and went through the review process and we were approved. Ostensibly that's why that section was labeled 'Approved for Release' in green.
But the button remained and we didn't think we needed to press it again. But apparently we did. In fact, even now in our dashboard it states that all sections are 'Approved for Release' while also saying our Store Page is "in the review queue". It makes no sense.
We've contacted Steam support about this. We'll see what they say.