I keep fresh dough ball in the refrigerator for 6 days to slowly ferment. I bake pizza in conventional oven at 245C for 6 minutes. On the 1st and 2nd days they bake perfectly, but I start to have problems on the 3rd through 6th days. They rise well, and stretch well, but do not bake at all. I use CMC powder for preserving dough moisture. I work the dough well. How can I improve baking on days 3–6?
the problem is that a dough made to last 6 days of refrigerated fermentation should be different that one made to be baked after 24 or 48 hours.
If you use a stronger flour (W=350) your dough will be great after 5-6 days, but not perfect before; to have a great dough after 24 hours you should use a medium flour.
If your flour does not indicate the W value (that can roughly be considered proportional to the protein level) try adding a bit (1/3) of Manitoba Flour to your next dough (but consider that it will be less good the first day)