http://www.neogaf.com/forum/showthread.php?t=1353294
So far this seems Amazon only. Mixed signals as to why. From defect to toxic chemicals. So far this is not everyone who pre ordered but quite a few so far. Me personally not yet but they could be cancelling in waves. So be aware. So far this is not affecting other retailers. Atlus is aware and looking into it.
So far people in the midwest USA have not been affected. Unsure about UK. It's not for sure known if it ties to when you pre ordered either. Many were January 2017 and on. I have seen one case of a June 2016 pre order cancelled. Canda now having this issue
https://www.reddit.com/r/Persona5/comments/5zyq5b/canceled_amazon_orders_megathread/df2ontw/