I know that this may sound like heresy
but sometimes a stall can be assisted along by giving the meat a bit of a shock like bouncing it on the counter. Also by foiling it at the point of stall.
I suppose that it breaks down the gristle and fats far better for a more tender end product if left alone to its own devices, but sometimes you just don't have the time. ( or patience )
The drop in temp during a stall is caused by the juices starting to move throughout the meat thus evening out the temps and causing a slight drop.
It just means that things are happening. Its frustrating though.
I have many times given myself an extra 4 or 5 hours to allow for the stall then have it stall even longer than that. It is at this point that Supuku seems like a reasonable solution.