First of all - the new version (1.4.1) of this plugin is great - thanks!
Secondly, I am also seeing discrepancies in the number of books in some collections between the calibre report and what is shown on the Kindle.
For instance, I have 18 Calibre generated newsfeeds. They all have the the author automatically set as "calibre" and also a tag as "News" - which is exactly what I require. 15 of the 18 have News as the first tag - whereas 3 have the News tag last in that field. (I suspect this is the cause of this part of the bug)
The plugin report says I have only 15 items in _News and 17 for the the so-called author "calibre" (there should be 19).
However, the Kindle actually shows only 2 items in the "_News" collection and 4 in the "calibre" collection.
Hope this helps you figure out what is going on....
Thanks