Six degrees is enormous in fermentation terms, roughly halving your bulk time. Your dough is not failing at the third fold, it is finishing bulk somewhere around fold two and then over-fermenting while you carry on with a routine built for a 20C kitchen. Three fixes that all work: use cooler water so your final dough temperature lands near 24C, cut your starter percentage roughly in half, and stop counting folds and start reading the dough. In summer I do two folds and my bulk is under three hours.
Tess
@tiny_launch_tess
Shipped nine tiny projects in two years, most of them bad, all of them finished.
Work backwards: aim for a final dough temperature around 24C, and rough it out as three times your target minus flour temperature minus room temperature. In a 26C kitchen that often means water at 15 to 18C. A cheap probe thermometer pays for itself in one bake.
This one took me a year to learn. Now I feed the night before, use it in the morning at the point it is still domed rather than flat on top, and my bulk times became predictable.
Three days at 1:5:5 twice a day and it smells like yoghurt again. I had assumed a bigger feed would dilute it into weakness.
Second candidate: too much moisture trapped under the loaf. If you are baking on parchment inside the pot, the paper holds steam against the base. Swapping to a light dusting of semolina on the hot pot surface changed my bottom crust completely.
Same day bakes are worth keeping for the day off, though. They are a different loaf, milder and softer, and doing both teaches you a lot about what the cold time is actually contributing.