Tartine Bread sourdough croissants

I've attempted the croissant Recipe from the Tartine Bread book. The outside looks good but inside is bready. Wondering if the roll-in butter is too little (approx 17%) ? It is a lot less than usual and also less than Tartine's original croissant recipe from their earlier book (Any thoughts on why?) The ingredient list is as below:

This Tartine croissant recipe is adapted from Chad Robertson’s Tartine Bread book.

 4.5 from 2 reviewsPrinttartine croissant recipe Makes 14-16 large croissantsINGREDIENTS

• 15 oz / 450 g milk (whole or 2%)
• 10 oz / 300 g leaven
• 13⅓ oz / 400 g poolish
• 2 3/16 lbs / 1000 g bread flour
• 5 tsp / 28 g salt
• 6 Tbsp / 85 g sugar
• 2 tsp / 10 g active dry yeast
• For lamination
• 14 oz / 3.5 sticks / 400 g cold unsalted butter
• ½ cup flour
• For egg wash
• 2 large egg yolks
• 1 tsp heavy cream or milk