Hello,
I have actually on SSD SATA installed these distributions: Linux Mint, Ubuntu Desktop, Kubuntu, Lubuntu, KDE neon, Fyde OS. All actuall version.
Screenshots are from KDE neon.
Command sudo update-grub not work correct for me. It finds only Ubuntu Desktop, no other distributions.
All screenshots are here
https://imgur.com/a/crvLj26
I tried unsuccessfully add Lubuntu on sda5 partition to GRUB. You can see it on one screenshot.
These guides not helped me too.
https://www.umutsagir.com/solution-to-os-prober-not-finding-other-operating-systems-windows-linux/
https://www.omgubuntu.co.uk/2021/12/grub-doesnt-detect-windows-linux-distros-fix
Dear developers. Can you please repair?
Thank you very much