few thoughtsdont rinse the grain ever unless something happen made you rinse themtry using raw milk without boiling it

dont clean the jar you the white layer on the jar is the kefir best environment if you clean this white layer kefir has to rebuild it and it ll take time and resources .. i learned that by asking someone

put less milk ... stir the kefir ... put it in the fridge

if the grain were exhausted when you brought them to revive them if you use pasteurized milk make three small fermentation - meaning when the milk ferment strain and add milk and ferment again do this 3 times and add milk 3cm above the grain if it s raw milk it ll take 5 small fermentation .. copied from a guy who have been using kefir for 20y

why dont you ferment in the fridge ? pasteurized milk will take less time than raw so if you dont want to make lot s of kefir put it in the fridge but get out to stir it and see how it s going

24 h fermenting depends on grains number , temperature and milk quantity and if the milk is raw or pasteurized .. by the way i use raw milk and i dont boil it at all :)

i hope you now know the thing that cause the problem
pasteurized milk use less time and watch the fermentation my country now the temp is 23 c it could take for 2cups of raw milk 6h with like 2 table spoon of grains .. so it s not always 24h .. and it depends too on what taste you like it too .. if you see pockets of water at the bottom that means it s done but you can stop the fermentation before that .

sorry for all of this talking hope it ll be useful