Were you on regularly? I would just be surprised if you paid for content and there wasn't a migration plan put in before 4/30.
Just because you make the effort to notify everyone and offer a migration plan, doesn't mean that people will pay attention to their e-mail, see it, respond to it appropriately, and in a timely manner.
I work for a company that attempted to migrate their customers from one old platform to a newer, better one, that sent out multiple notices to all
of their customers, with a link to click to migrate their old purchases over to their new platform.
Years later, and I am still dealing with having customers emailing us to complain that their old download links don't work any more, having to look up their old purchases in an old system we no longer use (except to look up old purchases of those who never migrated), creating vouchers to import them to our premium service where customers can just login whenever they want and download them again & again, without having to pay again or worry about losing old e-mail receipts with the download links...
And having to toss files related to discontinued products in Dropbox for them to download, because they waited so long that the old outdated books are no longer available in our voucher system.