I've been making sourdough loaves for some time now - largely with much success. However, I've recently developed a problem with oven spring. It just isn't happening really. My loaves are acceptable, but that final rise in the oven has stopped. Why? Perfectly risen overnight rounded loaves of springy dough go in the oven in a dutch oven and slightly flatten at the sides and only barely part at the slash... I'm so frustrated I'm near throwing it all in, as one should an abusive relationship devoid of any reciprocity.
I've read a lot on this and actually had this problem before (unsolved, as I relocated and started a new starter), so, just to eliminate any of the usual solutions offered:
1) My starter is healthy - rising x3 on a 1:2:2 ration
2) I knead either by hand or in Kitchenaid, never no knead pulling method. Whatever the case, I've had many, many, many successful loaves using this method. First proof, 5 or so hours, second proof 12 or so in fridge in banneton.
3) So, all the usual over-proofing, not active enough starter, not hot enough oven etc. solutions don't seem relevant here. I've changed nothing, it has just stopped rising in the oven.
4) The only thing I can point to is leaving the started in fridge for over a week - about 10 days - unfed. It was after this that things changed. However, I can't really see this as the cause, as the starter is back in fighting form. This is just the moment when it happened.
I've included a photo of past glory as well as recent failure.
Any help greatly appreciated! Thanks in advance