GRUB not booting using PARTUUID

[plangin]

I installed ZimaOS 1.1.0 Beta to the internal SATA SSD using the installer.

The 8 partitions are created and the boot partition is populated with GRUB and a grub.cfg.

But the UEFI boot menu does not recognize the OS, therefore it won't boot.

I checked the grub.cfg:

menuentry "Slot A (OK=$A_OK TRY=$A_TRY)" {
    linux (${boothd},gpt2)/bzImage root=PARTUUID=8d3d53e3-6d49-4c38-8349-aff6859e82fd $default_cmdline $cmdline rauc.slot=A
}

menuentry "Slot B (OK=$B_OK TRY=$B_TRY)" {
    linux (${boothd},gpt4)/bzImage root=PARTUUID=a3ec664e-32ce-4665-95ea-7ae90ce9aa20 $default_cmdline $cmdline rauc.slot=B
}

menuentry "Slot A (rescue shell)" {
    linux (${boothd},gpt2)/bzImage root=PARTUUID=8d3d53e3-6d49-4c38-8349-aff6859e82fd $default_cmdline $cmdline rauc.slot=A systemd.unit=recovery.target
}

menuentry "Slot B (rescue shell)" {
    linux (${boothd},gpt4)/bzImage root=PARTUUID=a3ec664e-32ce-4665-95ea-7ae90ce9aa20 $default_cmdline $cmdline rauc.slot=B systemd.unit=recovery.target
}

A blkid /dev/sda3 does show the correct PARTUUID=8d3d53e3-6d49-4c38-8349-aff6859e82fd.

Only when changing the first grub.cfg entry to /dev/sda3, ZimaOS will boot:

menuentry "Slot A (OK=$A_OK TRY=$A_TRY)" {
    linux (${boothd},gpt2)/bzImage root=/dev/sda3 $default_cmdline $cmdline rauc.slot=A
}