Just like in the fermenter, fermentation isn't always dynamic...It doesn't matter one blip in your fermenter or your starter flask if the airlock bubbles or not (if you are using an airlock and not tinfoil,) or if you see a krauzen. In fact starter fermentation are some of the fastest or slowest but most importantly, the most boring fermentations out there. Usually it's done withing a few hours of yeast pitch...usually overnight when we are sleeping, and the starter looks like nothing ever happened...except for the little band at the bottom. Or it can take awhile...but
either way there's often no "activity" whatsoever....
I usually run my stirplate for the first 24 hours, then shut it down, if you are spinning your starter it is really hard to get a krausen to form anyway, since it's all spinning, and there's often a head of foam on it from the movement.
All that really matters is that creamy band o yeast at the bottom.
As it is I've only ever seen two krausens actually on my starter, and the evidence of one on the flask at the "waterline" once. But I've never not had a starter take off.
