Originally Posted by seaquay
...I changed the column from 'kindle' to 'kindle_col' and both can be seen when customising the plugin in the plug-in GUI. Maybe there is a bug here....
I suspect this is because you must eject the Kindle and reconnect it any time you add/update/delete any books or columns. I'll need to emphasize this more. Although I mentioned Calibre might have some bugs in the metadata.calibre writing, its actually working as expected. We just have to be careful about making sure the Kindle's metadata.calibre file is always up to date - and the best way is to disconnect and reconnect the Kindle whenever you make any changes to Calibre.
Thanks for mentioning it - if it can be fixed, I'd like to fix it