You know, I've been reading a bit more about using diastatic malt powder (ground dried sprouted grain, usually barley) and how it affects bread, especially long-fermented bread. There's a good discussion of it here on the Weekend Bakery:
You only need very small quantities of diastatic malt, about 5g or 1 tsp (or 1% of flour weight) per loaf of bread to get good results. Because there is also something like too much diastatic malt which can result in a reddish instead of a golden crust, weak dough and a rubbery crumb. Add just the right amount and it will do magic for your loafs! Some brands of flour already have diastatic malt added to it, so look on the package to check. As a rule, most whole wheat flour and organic flour does not have diastatic malt added and your bread will improve when you add your own.
I know that many commercial flours seem to have a bit of malt added to them. Do you think this might be enough to be causing the problems that some folks are having with their long-fermented doughs eventually collapsing into a puddle? The issue seems to have some consistency in that people say the dough looks fine to start with, but by the time it comes to shaping or baking it it has turned sticky and very slack. I wonder...