Adobe Digital Editions doesn't show my purchased book on my iphone

I have the Adobe Digital Editions app on my iphone.  But under purchased books, or anything else, it doesn't have the ebook i bought earlier this year. I could read on my phone a couple of months ago.

And on my PC it has the book under purchased items, but I don't want to be dragging my PC around every time I need to refer to the book or if I am on holiday.

Adobe's customer support is hopeless.  I spent an hour on the phone to someone who said he wasn't trained and just directed me in circles or to things that didn't help, and they don't answer their live chat messages.  He also claimed they have a new well-trained team dealing with Adobe Digital Editions customer queries but there is no phone number for them!