I found something interesting on a new install: /etc/default/grub.ucf-dist has the os prober on line 17 However - /etc/default/grub has no mention of the os prober So my successful work around was this: Copy: GRUB_DISABLE_OS_PROBER=false from /etc/default/grub.ucf-dist into /etc/default/grub then run update-grub Viola - worked for me