This may sound stupid, but give the balancer a look as well. Is it on all the way? Is the crank bolt still tight? Can you spin the pulley by hand? Hopefully you got it lined up properly when you reinstalled it and didn't shave the woodruff key off the crank.
I'm wondering if the balancer isn't tight and walked out to the point where the CKPS can't pick up the interruper ring on it.