Sourdough not rising while baking

Hi all,

Ive been baking sourdough for a while now and while I learn about my starter, flour, proofing time and scoring with every loaf, one issue that repeatedly occurs is the spreading out of the dough at the score. My dough just refuses to rise up. 

These are the measurement I follow:

325gms organic white flour

12 gms vital wheat gluten (I live in a country where we dont get strong flours)

247gms water

9 gms salt

65 gms starter

I autolyse the flour, gluten and water for 3 hours, add in the starter, 30 min rest then the salt. 

After 30 mins, I do a stretch and fold in the bowl, 30 min rest then a lamination

Post the lamination, I do 4 coil folds, storing the dough in the refrigerator for 15 mins of the 30 mins resting to avoid over proofing during the bulk fermentation. (I live in a place that's warm throughout the year)

Next I do a pre-fold and then the final fold while gently knocking out some air during the fold. 

I proof the dough of 12-14 hours( at 6c)

Starter:

I store my starter in the refrigerator. The prior to making my bread, I feed it 3 times during the day and the leave the last feed overnight, the next day, I feed it one more time which I use as my levain when it has peaked. 

I feed my starter with a mix of organic white flour, whole wheat flour, ragi flour and 2% vital wheat gluten

Baking:

I bake my bread on a hot baking sheet with a dish inverted on top to retain steam. 

Any suggestions/ advice would be highly appreciated.

Thank You