Video walkthroughs on my Kansas City units got me two inquiries in a week, so I thought I'd scaled something

The inconsistency you're describing is almost certainly a demand problem dressed up as a marketing problem. Q1 in KC the rental market is tighter, people relocating for spring start dates are actively looking in February and March, inventory is lower. By Q2 you're competing with a wave of new listings and anyone who was going to move has largely already moved. The video didn't scale, the seasonal window did.

I ran into the same thing with a fourplex in Midtown, spent money on photography and a 3D tour thinking I had found some edge, got four applications in ten days, thought I was a genius. Tried the same approach on a garden-style unit in Raytown six months later, crickets for three weeks until I dropped the ask by $75 and the PM just called someone off her list. The asset and the timing mattered way more than the content. I'd be cautious about treating six weeks of silence as proof the video format failed, it might just be that those four units in Q2 were always going to be slower fills regardless of how good the walkthrough looked.