Stronger flour, weaker bread.
As I'm still a bit green, I've been using a supermarket flour (Asda) with excellent results; it's 11%. I was bought a fair amount of branded (Allison's) white bread flour, which is 12%. - and I'm having failure after failure.
The symptoms are that the loaf doesn't really proof properly, slops all over the place so that it flattens in the oven, then has immense oven spring - resulting in huge wholes in the middle of the loaf. After drop-kicking a fourth failure and conceding defeat, I thought I'd ask here. I used Allison's many years ago for normal yeasted bread, and it was fine; has anyone encountered any flour that seems to just plain suck for sourdough?