I have used an Annual Passholder discount 9 times during the last five years and have YET to be asked to show my Pass at check in.I have even been asked if I needed park tickets at check in.LOL

You may possibly be asked by a check in Cast Member to produce a Pass,but that has not been my experience.The worst-case scenario is they will go ahead and check you in and tell you to bring your activated Pass by later that day.If they will not allow you to check in using your voucher ask to speak with a Manager.There is an EXCELLENT chance you won't even be asked to show it.