My sourdough splits at final proofing (pic included), advice? The last couple of times I've made bread the dough starts "splitting" during final proofing.  

Does anybody have any idea why? The bread is still great but it doesn't get as much oven spring as I'd like.
There are three likely causes: over-proofing, insufficient gluten development, and too loose shaping. Some combination is probably most likely. To detect over-proofing try the `poke-test': if the dough springs back immediately, the dough is under-proofed; if the indent stays as it is, the dough is over-proofed.

I've found Dan Lepard's advice in The Handmade Loaf for shaping high-hydration sourdough loafs very useful. After final stretches-and-folds, spread the dough into a circle, and make eight folds into the centre, pressing down on the join. Use the scraper to invert the dough and rotate it gently on the work-top for a minute or so. This tightens it up. Then invert it again as it goes into the banneton.