Single book won't sink on Kindle apps

I’ve check Whispersync on Amazon and on the apps, it’s turned on. But one book will not sync (reading it on my iPhone and iPad and won’t sync on either.) FWIW, book is The Stand, Stephen King, and purchased from Amazon.

Other books will sync no problem, just not this one. Any ideas? Can’t find anything on Google.

Stupid question I know but have you tried reclogging on both apps. Had an issue with the Kindle app once that needed a relog rather than a restart / reboot

I came here because of the autocorrect.
Since this isn’t the problem that was advertised, I have nothing to offer (excepting you are lucky to have sync working: here, juggling a couple of amazon store accounts, everything gets erased regularly for my heretic multilingual ways).

This has happened to me, I had to disable all my old kindles and devices. Google up ‘manage kindle’