Indexing issue, kindle Voyage

[HFM1101]

Hi,

I have 874 books on a Kindle Voyage. I know that they were at one time indexed, because it took me a long time to put the books on in batches to allow for that process.

Today, I went to a book to search for something and the search function tells me there's no results. I've done this for a great number of books, and none of them are indexed.

When I'm on the home page and search for a made up jumble of letters, it finds 8 books that have been indexed.

I know that these were once indexed, and now they are not. What could be going wrong? I've tried restarting the device, both manually and also via the menu. It has not changed anything.

Does anyone know what is going on, and can anyone suggest anything? I really do not want to remove all 874 books and spend a week putting them back on in batches of 20.

Thanks.