Uh oh -- beginning swimmer in deep water!
After succeeding with a few oven-baked loaves, I thought I'd try this recipe, a Dutch Oven Sourdough Sweet Potato Crunch Bread.
I used my new Kitchenaid Classic Plus stand mixer for the first time. I started with the lower amount of water (325g) in the recipe, reserving the balance of 75g for contingencies. Contingency: the mixer was having trouble mixing; parts of the concoction were climbing out of the bowl. It seemed too dry to me, although I may be biased as my meager prior experience is with high-hydration recipes, and at 325g the hydration here was 54%. So I added the reserved 75g (bringing hydration to about 66%) and that seemed to help the mixer mix. But just as the ingredients seemed to be reasonably-well mixed, the concoction was so sticky that it was all stuck to the dough hook and just spinning around en masse with the hook. I changed from the dough hook to the flat beater with the same result.
So I abandoned the stand mixer and went at it with my hands for a while. I had no idea when to stop, but I did stop.
At this writing it's thirty minutes into the bulk fermentation. Soon I'll do the first stretch-and-fold. Herewith a picture of the dough 15 minutes into the bulk fermentation. I don't know why the top portion of the dough appears to be a different color than the bottom portion; it's not a mere artifact of photography.
It looks like the dough reached up where the hook locks onto the gear that holds the hook. There is a dark lubricant in that area of the machine that could have gotten into your dough.
I suppose that's possible, but I spent quite a while mixing with my hands after I gave up on the mixer.
I examined the area in question and don't see a source of lubricant. The dough hook has a circular guard below the locking mechanism, and also I see no lubricant in/around the mechanism.
...Be asymmetrical.
It wasn't lopsided going in to the oven!
This is the second loaf. As I have a small one-loaf oven, after final-proofing this one for about 45 min., I put it into the refrigerator in the banneton, covered, for about 8 hours, then back to the counter for a couple of hours before baking.
Also, I didn't use the Dutch oven; I used a baking stone with pans of lava rocks underneath which I hydrated at the start of baking. The idea was from this thread. I find the Dutch oven unwieldy as compared with the stone. The crust is darker than the first loaf's with more burnt areas. The internal temperature was 204F, while the first loaf's was 195F. Each baked for 45 min.