I brought this up on systemd-devel the other day and Lennart agreed that it is a bug in systemd that it refuses to start services that depend on masked mount units when the mount is active. He advised me to file a bug report on github, but github insisted on emailing me before allowing me to log in even though I know my login and password, and they seem to still have my no longer existing ubuntu email address, and so I am locked out. Their contact us page also does not seem to work nor have they replied to my attempts to email support@, so I am unable to file the upstream bug.
He also advised that gparted should be using a bsd file lock instead of masking mount units. Curtis Gedack wasn't sure about making the change at least for the upcoming release of gparted. Perhaps after that.
