Lack of cm

I always always always can tell when ovulating based on cm. I've been off the pill 4 cycles and they've all been 27 days long and cm starting around day 10, slowly increasing for a few days. Very regular and cobsistent...whoo hoo. We started trying this cycle and no cm...according to glow and my cycle patterns I've noticed , yesterday was my peak day but I've had nothing!...any reasons for lack of cm? it's just confusing because it's been so reliable up until the cycle I really need it to be. ...we still bd 4 green fertile days in a row ... would I still have ovulated without it?!....thanks for your thoughts :)