The 'current' AP cards have 2017-2018 dated onto the back. We didn't get them until about April, if I recall correctly, so we were still using the 2016-2017 ones until then. The 2016-2017 ones should continue to be accepted through the end of the year for discounts, because... it's still 2017.
2015-2016 cards shouldn't be accepted, but plenty of merchandise and food service CMs don't care and/or make exceptions and/or just don't notice. The even older cards that were green with a character on them and either an orange or black stripe REALLY shouldn't be accepted.
With regard to Guest Relations - they're very good at problem solving, but they really don't know everything about tickets and passes (if they did, my job wouldn't exist). They're too busy trying to appease people who want something for free because of a minor issue.