Clicking "attempt to support newer firmware" worked for me too, but only kind of.
After adding a new book to my KT, disconnecting KT, 75% of the time it doesn't process the content, and when it doesn't, the new book I added doesn't really show up on my KT.
It will look like it's there, the cover will be on my homepage, but then when I click to read the book, KT will smile at me and think and think and think, then go back to home and the recently added book will have disappeared.
Now, 25% of the time, KT *will* process content after I disconnect, but I'd really rather that be 100%! Sometimes I'm in a hurry, peeps ;D
Anyway, will there ever be a calibre fix for this I wonder???? It would be super!