unusual gluten behavior: regression after bulk

Hi TFL friends,

Maybe you can help me to understand what happened with my bread today.

My dough completely regressed during bulk fermentation, and then came back with machine mixing and turned out with the best texture I've gotten so far?!?

I'm baking 100% whole wheat loaves with a Concentrated Lactic Acid Sourdough (CLAS) culture and commercial yeast. My total flour weight, including in the CLAS, is 1000 grams, and my hydration (including 200 g scalded milk) is 85%. My flour today was fresh-milled 360g hard red winter, and fresh-milled 560g Kamut khorasan. There is also 80g rye, from the CLAS. I sifted the flours to 94% extraction and did a bran scald.

First I mixed the flours with the scalded milk, water and CLAS, and let rest/autolyse for around 30 minutes. I did some stretch and folds, and the dough was lovely, silky and extensible.

I combined the yeast with the bran scald and the sugar, spread it on the dough, and folded it inside, then sprinkled on the salt. I mixed until the dough was homogeneous. After a few minutes of mixing the dough became softer and very sticky. It made windowpane, but with a tendency to tear around the edges.

Bulk fermentation wad almost exactly 2 hrs. At the end of that time the dough was 1.5x original size, and was no longer smooth. It had developed a coarse textured appearance. Attempting windowpane was impossible: the dough had zero strength, elasticity, or extensibility. It was intensely sticky and wanted tho come apart onto everything it touched.

I divided it into 2 loaves, rolled one up and stuck it in a loaf pan to final proof.

The 2nd loaf, I decided to take another shot at developing the gluten, even though I've never heard of doing this after bulk fermentation.

So, after 4 minutes of mixing on low speed, the dough had recovered. The windowpane was back.

The dough was a bit less sticky (but still quite sticky). It went into a rice-floured cloth-lined banneton. Once proofed it went on a cookie sheet, got scored, covered with a lid, and baked. During the bake it spread and flattened.

Once cool, this bread had a thin, crisp, delicious crust, wonderful rich flavor, and seriously the most delicate, soft, fluffy crumb I've personally ever eaten in a whole wheat bread.

It's so good.

What the heck happened?

Crumb shot for perspective, even though it doesn't look like anything special. You can't tell from looking how soft and tender and fluffy it is!