Wes

Patchy fur at hour 30 is roughly on schedule and the smell arrives late. My timeline: hours 0 to 18 nothing at all, 18 to 30 faint sweetness and the first white haze, 30 to 40 it starts generating its own heat and you must break the bed apart or it cooks itself, 40 to 48 the chestnut and mushroom smell shows up properly. The heat generation is the part beginners miss. Once it starts warming itself, furrow the rice into ridges and give it air, or you will get a hot core and dead spores in the middle.

Check the airlock is actually sealing before you diagnose anything else. Half my "stalled" ferments have been gas escaping past a lid gasket. Give the jar a gentle press and see if the airlock moves.

Definitely a flat sheet, no colonies. Skimmed it and it was back thinner by the next day.

For anyone finding this later: two weeks on, the kraut is sour and crunchy and there was no further drama after skimming.

If you want the slime gone faster, rest the grains in fresh milk in the fridge for a few days. Cold slows everything, the ropey strains lose their advantage, and they come back normal. I would not rinse them in water, and definitely not tap water.

Cheaper option that works: a small ziplock bag of brine sat on top of the cabbage. It moulds to the jar shape and seals the whole surface better than a rigid disc, and if it leaks you have lost nothing since it is the same brine. Fill the bag with brine rather than water in case it does.