the x-ray plugin for calibre seems only to work for azw3 and mobi files, it doesn't seem to support kfx format that I can tell anyway.
referring to my edited post under page 5 about this plugin, also I have to learn how to manually put the thumbnail under the device for kfx format still, I am new to understanding it since I just found out in the last day about this new format.
again it seems best to use calibre input format rb format to out format kfx format, without conversion errors from epub since the kfx plugin seems to convert the RB format into epub then outputs it to kfx format, that seems to keep the conversion errors from happening in the few ebooks I tested today.
to not get the error below when converting from epub format to RB format into kfx format, make sure your source from epub format to rb format, has under structure detection the box label insert metadata as page of start of book that feature needs to be uncheck at all times when going from epub format to rb format, also needs to be unchecked when converting from rb format to kfx format, otherwise you will get the error below, I was able to convert my ebook once I made sure that feature was not selected in calibre.
Error(YJConvValidator):E120013: Data table found in the book
https://www.mobileread.com/forums/sho...=272407&page=5