Universal Audio Apollo no longer works with Zoom after multi-channel audio update

For years, I used an SM7b mic through my UAD Apollo (Silverface with a thunderbolt/USB-C card). However, it's audio quit being detected in Zoom a few weeks ago when the "multi-channel audio" feature was added to Zoom. I've tried turning on the "Use specific audio input channels" function and selecting every single channel. Doesn't make a difference. The input level meter in Zoom's audio preferences doesn't move (despite being pegged on my device), and no one hears me in calls.