Calibre 8.10m in Linux Ububtu does not recognise Kindle whitepaper

Dear All,

I am new in this forum, actually new in any forum,

I have Calibre 8.10 type FlatPak installed in a Linux Ubuntu 24.04.3 as operating system. When I connect the Kindle tuothe PC via a USB port Calibre does not recognize Kindle.

Calibre does not recognize the Kindle even though Ubuntu does, and the Kindle itself displays “Connected to the computer” on the screen. I have tried everything: reinstalling Calibre, restarting the PC, trying different Calibre formats that were not Flatpak, calling Amazon and having them send me a new Kindle, trying different ports and USB cables. But I still can't get it to work.

Does anyone have any ideas about this?

Thanks in advance.
Mauricio