Ciabatta with large air pocket
I just made two loaves of 75% hydration ciabatta ('King Arthur Flour Rustic Italian Ciabatta' recipe). One came out nicely. The other looked like pita bread, with a giant air pocked under the crust and no inner crumb. These were part of the same batch, so everything should be the same, with the exception of the bad (pita) loaf proofed an additional 25min while the first was baking. Could this additional proofing time cause this (over proofed)? I had read some other posts about lack of gluten development causing similar issues, but that didn't seem to apply here, as the first loaf was fine. Photos of the 'good' and 'bad' loaves. Any suggestions?