Bizarre boot chaos across two drives (raw disk clone with dd)

For one thing make sure this line is uncommented:
/etc/default/grub

GRUB_DISABLE_OS_PROBER=false

(and run sudo update-grub again)

For the rest … you probably need to include some actual information, such as blkid, lsblk, cat /etc/fstab, etc.

2 Likes