This was my attempt following your course! I did 350g flour, 280 bread flour (12.7% protein) and 70g whole wheat (13.2%) and 70% hydration. It was quite wet as I was trying to do the slap and fold technique, but humidity was 75% that day, so maybe that was it? It came together nicely during stretch and fold/coiling, though, and right before baking it felt good (bouncing back slowly with a slight indent). 

I misted it with water in the dutch oven, but it didn't rise much. Maybe 475 was too high for my oven, the bottom of the loaf was darker and tougher. I'll have to get an oven thermometer. 

 

I learned so much, though, and I'll keep tweaking things. Thank you for explaining things in a way that's so intuitive!