Title says it all really. Books in iOS12/macOS Mojave won't sync with it's counter part in iOS11 or macOS High Sierra. I appreciate they have updated the structure of the app but to not even keep page syncing is pretty ridiculous.
gone are the days when the minimum requirements used to be two versions back
If you look the changes in iOS 12's Books it's pretty easy to see why the syncing isn't compatible. Not the first time either as I believe one of the Notes versions wasn't compatible with older versions once you updated (iOS10??). When you make data structure changes, continuing to support older versions oftentimes creates too many issues.
On a different note, Books in iOS12 is so much better (loved that they've brought back the Wish List with the "Want to Read" section). The whole browsing and viewing the store has been greatly improved as well.
This has been an issue since Developer Beta #1 and Public Beta #1. I've left Feedback via the Feedback app, though I highly doubt Apple will do anything to fix this issue, other than to tell people to upgrade. I do agree with achappy in that Books is much improved in iOS 12.
Yeah. I'm aware changing data structures can make things tricky. The problem is they don't tell you until after you upgrade a device to ios12 or macOS 10.14 that your other devices will need to update, even if some of those devices are incapable of running said upgrades. It's the blanket assumption they everyone will have a compatible device that's the issue not a data structure one. Although, for a company that wants to do more services, only supporting the most recent release is overly narrow.
iOS12 and Mojave are being supported on a large number of devices up to 7 years old. How long are they suppose keep supporting OSes? As a software engineer, when you opt to continue supporting older devices/schemas/OS, you make design sacrifices that aren't needed if you just do a hard cutover. Building in support, even for something as simple as page syncing, so you can sync across devices to older OS versions often leads to less than optimal code and design choices. Given everything that's in iOS12 Books, it was no surprise when I saw the warning about syncing.
It was the same thing with iOS 9 and Notes which was not backwards compatible and it was documented quite a bit as well as on the Apple's support site.
Simple solution (According to Apple) ... buy a new MacBook. Dayum. That sucks. I have a 2011 MacBook Pro which is just fine for what I use it for but it won't run Mojave so I'm stuck too.