I was just talking to someone this morning who is down there now, plus they work as an independent Disney trip planner and asked them this exact question. She told me that in 2017 everyone who had Canadian tickets had to get them verified at Guest Services, but last year they changed it so that if the Canadian tickets are part of a package, they can now be verified at the time of check in at your resort. If you bought the tickets separately, you'll still need to go to Guest services. I'll put this to the test on Sunday.