I’m not sure what to say, it does sound like it is your autolyse. George de Pasquale did show me how you can sometimes create little flour nuggets, pellets, if you are not careful with your flour/water mixing. I’ll see if I can find that video footage. I don’t have that challenge with the autolyse but that doesn’t mean we shouldn’t create a solution. I might suggest that you chunk up your autolyse even smaller as you layer it into your Ankarsrum. See if that doesn’t help distribute within the Levain a little more effectively and moisten up those nuggets.
For doughnut, increase speed. 4:00?