Another FWSY overnight white question

Hi all,

So I'm usually sourdough baker and recently thought I would start making some yeasted breads so bought FWSY. 

I've attempted the overnight white twice now and also read quite a few other threads but haven't quite got my answer.

First time, 14 hours bulk at 25degrees ambient, about X2 increase in size. Shaped with no problems, I'm used to Hugh hydration sourdoughs. Proof 1 hour. Turned it out and it collapsed and I could barely score it. So read a few topics and figures I had overproofed it.

This time. 11 hours bulk, 23-24 degrees dough temp. Just over X2 in size. I watched it throughout the day. Again, nice straightforward shaping. 45min proof, turned it out and pancaked again as before, struggled to score. The photo is the crumb this time round. 

My thoughts, pancaked as if I had overproofed it, but crumb almost looked as if it's underproofed and there was still too much gas being produced. Could it be that there was still so much gas production that it broke down the gluten structure and that's why it collapsed? Maybe a longer bulk is required, closer to x3 in size? Any help would be great! For some reason I thought yeasted breads would be more straight forward than sourdough.

Thanks!