Please have a look at this thread:
https://www.mobileread.com/forums/sh...d.php?t=351285
Effectively those of us who use a Kobo ereader, can't read any new kindle books (published after the 3d of january) anymore on our Kobos.
I used to buy my books with the 1.17 Kindle for pc app, which allowed me to load the azw file in Calibre and then upload to my Kobo Sage. Amazon has blocked this 1.17 version and forces the customer to use the latest version which downloads only the KFX file which can not be read in Calibre.
This is too bad. The power of Amazon is such that many authors publish exclusively in the Kindle store. Their (new) books can't be bought in other online stores.