Who had trouble with position at the bottom of the snatches? Meeting the bar "down there" is completely different from squatting the bar down there - as in the OHS - and success depends a lot of your position and stability when you receive the bar.
It's a pretty unforgiving place to be and demands consistent practice. Lack of flexibility will make this practically impossible -- but flexibility where?
It's common to automatically think shoulders are the culprit but it's not true in all cases. Could be your hips. Or your lazy squat. MWod explains it here: