Hard links are reported as duplicates

[Bart Brouns]

Thanks for this wonderful program!

myDirectory is a dir with 4 almost identical copies of a certain file tree, deduplicated using hardlinks.
When I run fclones group myDirectory, all of those hardlinks are reported as duplicates.

I checked if they really are hardlinks using ls -i.

Some info on my system:

OS: NixOS
fclones 0.34.0
fs: ZFS
kernel: Linux 6.5.9 #1-NixOS SMP PREEMPT_DYNAMIC Wed Oct 25 10:16:30 UTC 2023 x86_64 GNU/Linux

Sorry for the vague and probably hard to replicate bug report.
What can I do to troubleshoot?