With you on this. Had the exact same issue with my last secondary rack. Even accidentaly pushed one stopper through into the boy as it was slippery as all hell from the starsan soak/rinse. Gave up on the second stopper attempt as it just kepted coming out (had a vodka suck back issue too, but that is a different story). Switced to a 1 inch blow off in a deep bucket of starsan water. Beer is chilling fine ever since. Not sure I will use the stopper again. blowoff iss easier (for me), and seemingly safer at this point.