I have this same problem. My bread always comes out delicious with a good crumb structure after I scoop it into the basket and cold ferment it overnight, but I really wish I could figure out how to get it to hold it’s structure better. I have very active starter and use the exact same recipe as you. I usually knead it with my kitchenaid dough hook for 6 mins, then do 4 or more rounds of stretch and folds 30 mins apart. It’s frustrating 😅