Comment # 10 on bug 1220276 from Michael Chang

I suspect that the issue arises from Fedora's use of BLS (Boot Loader
Specification) in its grub.cfg for the linux boot entry, deviating from the
native `menuentry'. Consequently, the parsing process encounters a challenge
with /usr/lib/linux-boot-probes/mounted/40grub2, as BLS is not universally
supported in grub. Fedora takes a unique approach by not utilizing /boot/efi
for the fragments, further complicating the situation. Essentially, even
systemd-boot fails to detect and multiboot it.

To verify this hypothesis, could you please execute the following commands with
root permissions:

> since=$(date +"%Y-%m-%d %H:%M:%S")
> export OS_PROBER_ENABLE_DEBUG=y; grub2-mkconfig -o /dev/null
> journalctl --since="$since" > /tmp/os-prober.log

Kindly attach the os-prober.log file here for further analysis.