If the dracut option works, that's a weird bug in my opinion. Automount shouldn't be attempted by systemd until root FS is mounted at which point Btrfs module can be found.
Can you reboot the failing system and post a clean journal for this boot?
journalctl -b | fpaste
Might fail if it's too big for fpaste. So it might have to be put up elsewhere.
Also
cat /etc/fstab | fpaste
Chris Murphy