*Cannot* get that "Oven Spring"
I've since figured it out. Gluten free bread is very particular, and the moisture has to be just right. If there's not enough water, the dough is too dense and won't rise. If there's too much water, it will rise, but in the oven, the bubbles bubble through the too, causing the loaf to collapse (I sat and stared and watched it happen). I've since learned what the dough must look like. It looks like thick cake batter. Should be smooth looking, but not soupy.