@srdjanprpa Take a look at this discussion:
https://www.mobileread.com/forums/sh...39#post4462739
My guess would be that it looks like newer firmware builds probably have a bug related to using Calibre generated & transfered .apnx files (those contain page count mapping information) that are needed for both old mobi and newer azw3 book formats (the latest format KFX has that information internally).
And since your Kindle model's factory firmware is newer then firmware build other people started noticing problems with missing page count progress indicator there really is nothing for you do to other than hope that the problem gets fixed in future updates.
That is assuming Amazon didn't break it intentionally
People with older Kindle models could at least hope to jailbreak their Kindle and then downgrade firmware to an older bug-free version... but for your 12th gen there isn't any older firmware than the one it came out with.
Kindle firmware keeps getting progressively worse and more buggy with each update. .. expecially since Amazon hired people to rewrite most of Kindle UI using React Native.