My PRS-700 will not allow me to save books with collections over about 4GB. I have tried 8GB and 16GB ProDuo and SD cards. Below the 4GB the books and collections show up on the reader. When I go over, the books are there but no collections. When I reconnect the reader to Calibre it shows that all the tags have been deleted

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Has anyone experienced this? I've used Sony and Lexar MS and Kensington, Sandisk and Patriot SD cards.
Any help woudl be greatly appreciated.