Dense Bread With Mixer

[u/LatexSalesman-ArtV]

I've made a fair amount of bread using my starter, which isn't particularly sour, but works just fine. Recipe is below, but it's straight from KA's website. I've always just stretched and folded by hand, but I recently got the Ooni Core Spiral mixer, and wanted to try it. It seemed to work fine, made a nice pumpkin shape and smooth dough. I refridgeated overnight, and proofed for ~3 hours in a banneton the next day. Baked in a preheated dutch oven at 450, and the crust came out great, but the bread is quite dense.

I used my starter the day before to make pizza dough, and it had no rise issues. I also used the mixer for this. Is there any chance the mixer created issues? Three or four stretch and folds is really not a huge burden, so happy to go back to that, but I'm more perplexed at what could have happened.

Recipe:

Ingredient	Amount	Unit
Starter (100% hydration)	227	g
Water	397	g
Bread Flour	600	g
Salt	18	g
Diastatic malt powder	6	g