some time in the past year, my sabayon linux grub2 install has stopped seeing unmounted distributions when i run grub2-mkconfig > whatever.cfg. i've got over 30 distributions on this machine, and i occasionally use the sabayon grub2 to boot some of them. i'm having to stay with an old config that i wish to update. i just noticed today that it was only seein mounted distros. i mounted a few others at various mountpoints, and ran the grub2-mkconfig, and they were seen and entries were created. i reinstalled os-prober, but it didn't make any difference.

Did you update / re-install GRUB2? Are those "unseen" distros on something like btrfs or zfs?

^ could be: https://askubuntu.com/questions/9671...trfs-partition

A general search for the topic