@Loeffel
Hmm - sounds a lot like I experienced.
However I run Vista64, but ... not important I think.
In january I didn't really want to start over (again), but renaming metadata.calibre, reconnect etc. having Calibre re-create the file, it was just way too small, still missing imformation.
Ran fw 3.0.3/run fw 3.1, no mods/jailbreaks.
I suggest you do a backup of what you've got on your K3 first off all.
Then try to re-send a problem book to if anything changes.
If not, try to delete the book on K3, send it from calibre and check.
I tried to fix it this way, but didn't work out (can't remember the calibre version)
I'm NOT recommending you to do the following, unless you're sure:
I did a full backup of my K3 just in case.
Then I did a factory reset of K3
Send books from calibre ( not too many at once ) and wait for indexing to finish.
Collections I setup using meme's Kindle Collections plugin.
I did have challenges with the old annotation files, and never figured a smart way to fix.
Since then I've had no problems.
BUT ... I've changed my rutines since then.
Before plugin in K3, I make sure Calibre is not running.
Then I connect K3, make a backup copy of *.calibre files and maybe the collections.json.
Now I dare to start Calibre, wait, and then wait. Do what ever I want to do (send books, fetch annotations, manage collections etc.)
Once done in calibre, I wait at least 1 min. Shutdown Calibre, wait 1 min, from Vista Explorer, eject K3, wait a bit and then safely remove (not in win7)
This has worked for me fine since january,
Why did it happen ? Well, I might have been too fast disconnecting at some point (incredible I know
) or a windows update did something strange.
I don't the calibre windows eject function has changed in ages. Kovid is not too impressed with windows usb functions
Hope this makes sense, and might help you along.
I suspect you're like me - Calibre and device info MUST be in sync and correct !
Cheers, Per