Previous setup, I had Bunsenlabs (from what I understand 99% vanilla debian just has Openbox/conky/tint2 and some additional scripts on top) installed in an LVM and efi with no issues.

I shrank my /home, created a new lv and installed Manjaro there, pointed to the existing fat32 efi location. I had to manually update /etc/fstab after the install to point to my existing lv swap as the installer wouldn't let me but that's working. grub2 is there, I get the options for Manjaro or Bunsenlabs and both boot fine.

The problem is I now have a ~5 year old bug to do with grub2 that I can't fix.

Error: diskfilter writes are not supported

'quick_boot="0"' was already set

I tried adding 'GRUB_SAVEDEFAULT="false"' but that didn't change anything

I've also replaced the section of '00_header' with the section of code that people said solved the issue that have an LVM configuration.

And yes I've run 'update-grub' at least a 1/2 dozen times, running for each change and reboot.

Any ideas greatly appreciated.