Syncing audiobooks across different Apple devices

I have recently started listening to audiobooks while exercising. I originally started with Audible and had an excellent experience wit the program. I decided to try the Apple Books app as I am an Apple guy (Mac, iPhone, several iPads, and Touch). However, the app has consistently and persistently failed to sync the prgress on the book from one device to another. It doesn't matter which platform I use. The Mac's listening experince is not recognized by my iPhone or iPad. This is really quite irritating. Has this always been a failure of the app or is this something new?