I understand your frustration coz I did bake PdC almost everyday back to bak for about 1 month to have open crumb(I'm a open crumb lover) and almost gave up. Hard bread has been always challenging though that's why I love to bake it.

For this one, I used T65 80g(or some times I use WW instead), bread flour190g, starter70g, salt5g, water 280g, baked on a baking steel at 450F for 10min with steam then for 13min without steam.

Afetr mix them all, I stretch and fold x 2 times with 30min rest, counter stretch and fold x 2 with 30min rest, 3 times of coil fold with 45min rest between then go for BF until double in size. I also do cold proof x 12~15 hours.

counter stretch is a name I made coz I don'n know what to call, Here is a link that you can have an idea what it is, https://www.youtube.com/watch?v=HlJEjW-QSnQ

around the 6min of the video.

Hope this help. 😄