systemd-gpt-auto-generator doesn't mount EFI system partition

according to the documentation, the systemd-gpt-auto-generator should automatically find the EFI system partition and generate a mount unit to mount it on /efi. However this does not appear to work on my system, despite all the requirements being met.I have an NVMe drive, /dev/nvme0n1, the EFI system partition is /dev/nvme0n1p1, and I'm using systemd-boot to boot the system

• There is a GPT partition table
• /dev/nvme0n1p1 has the correct partition GUID code for EFI system partitions, C12A7328-F81F-11D2-BA4B-00A0C93EC93B, and I can boot from it just fine
• The PARTUUID according to blkid /dev/nvme0n1p1 is 6ebb8123-f305-404b-b5a3-65f46c7d7076, and this matches the content of /sys/firmware/efi/efivars/LoaderDevicePartUUID-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f
• I'm not booting in legacy (BIOS) mode
• The directory /efi exists on the root file system and it is empty
• no mount point for this partition is configured in /etc/fstab. There are no .mount units for it either
• there is no extended boot loader partition (XBOOTLDR)
• the generator is not disabled using the systemd.gpt_auto or rd.systemd.gpt_auto kernel cmdline parameter

I could just create an entry in /etc/fstab and be done with it, but I would rather understand why it's not working. Any pointers on how to debug this?

I've tried running the generator manually:

mkdir /tmp/{a,b,c}SYSTEMD_LOG_LEVEL=debug \  /usr/lib/systemd/system-generators/systemd-gpt-auto-generator /tmp/{a,b,c}

But the output doesn't contain anything useful:

Found container virtualization none.Disabling root partition auto-detection, root= is defined.dm-3: Not a partitioned device, ignoring: No such file or directory