ok, so I fixed my subfolder problem by configure the Calibre device icon, option where you can configure this device "Configure amazon device" box and unclick Use Sub Directory's option, that should fix it so now all files are put into the document folder and not sub folders, I don't no fix that will fix the hard rebooting problem that just started with the newest firmware, I just notice that when I went to use my kindle paperwhite 2 tonight it was in the process of rebooting the device, not sure if I left it in an eBook or if something in the newest firmware is causing the Kindle paperwhite gen 6 hardware to reboot itself, so again I don't no why it was starting up when I pick up the device and open the e-readers case tonight was in the process of rebooting the kindle on its own when I had grab it from my computer desk, in any case if it stores all the KFX output plugin formated files inside the main folder, from calibre it should be no problem for it to generate thumbnails with ExtractCoverThumbs_1.0.0-py now, of course that doesn't fix the hardware problem that just started yesterday when I updated its firmware.
https://s3.amazonaws.com/firmwaredow...v2_5.9.6.1.bin
https://www.amazon.com/gp/help/custo...deId=201307450
Just wondering is it better to use calibre and change the compress images loseless to enable lossy compression of JPEG images to make say an 80MB or 50MB sized epub ebook before converting them to azw3 or kfx format for your kindle paperwhite 2 device to keep it from hard rebooting on free ebook etc or, use kindlegen and enable -gif format to change the jpeg and use say something like kindlegen -c2 -gif %1 settings for a bat executable command line option for changing jpeg into -gif format, is that smaller or better option when viewing the images on your paperwhite device, making this a bit shorter for that user etc.. that reply back , anyway I am not sure how much quality to lose when resizing jpeg images, since it seems when using a setting like 40 under enable lossy compression of jpeg images that it creates spots in the images, but at the same time it does make the total ebook size smaller, which may be ok for an paperwhite 2 device, but not my android 10.1 tablet you may notice more image artifacts under that hardware, I guess I could keep two copy's of the same ebook with different settings for both devices, just wondering if you use the jpeg settings or think that using kindlegen with -c2 and -gif and then use say the plugin Kindleunpack afterwards etc.. to make it better since it splits the mobi and azw3 files apart but of course it seems that their new kfx format is bigger than just using the older formats when using the kfx format, its both an mobi and azw3 total inside the file I think, if you understand that Kindleunpack cannot split the kfx format file, which is what amazon is using in their new mobi format (kfx format I think since kindle preview 3 outputs the converted files as mobi format with kfx in them if I understand the app itself right.