I updated the top comment, but you got me looking closer at the device list. It seems that v4l2loopback and my webcam were interfering with each other. rmmod-in

I updated the top comment, but you got me looking closer at the device list. It seems that v4l2loopback and my webcam were interfering with each other. rmmod-ing v4l2loopback, running the mopprobe myself, unplugging my webcam and plugging it back in seemed to resolve it.