Kindle books messed up after backup/restore

anon(8198425)

Member
Oct 31, 2013
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Got my Nexus 5 today and used Helium to make a backup of my Nexus 4.
After restoring my Kindle app, I found that when I try to read a book it says it isn't valid and I need to remove it from device and re-download.
I have it so all the new books I haven't read are kept on device, then I remove them from device as I read them so I can keep track.
So since I go through so many books I have no idea exactly which I have read and haven't read.

Used Helium a couple of times before with no issues, anyone have any ideas what I can do to sort it?