Thank you for your reply.
First of all sync all items using the procedure below. Be sure that your Kindle is connected to wifi internet.
From Home, tap the Menu icon (3 lines icon), and then tap Sync & Check for Items.
If that doesn't help switch the books view setting. When you open the books content page, tap the Menu icon and check if there is an option "List View". Check if that works.
If none of the previous solutions works log into Amazon and check the "All Items" list. If there is a book on the list that is not on your Kindle use the procedure below to transfer it.
1. Log in into your Amazon account - click here
2. Go to Manage your Kindle
3. Find the book on the list you want to transfer. Click on the "Actions..." dropdown beside the title and select "Deliver to my..."
4. Select the Kindle device you will transfer the file to and click the "Deliver" button.
When done, reboot and sync your Kindle.
Please let me know if that works. I'll be waiting for your reply.