An explicit reload should not be necessary for "enable".
I also can't reproduce the problem:
$ cp /usr/share/systemd/tmp.mount /etc/systemd/system/tmp2.mount
$ systemctl enable tmp2.mount
Created symlink from /etc/systemd/system/local-fs.target.wants/tmp2.mount to /etc/systemd/system/tmp2.mount.
An explicit reload should not be necessary for "enable".
I also can't reproduce the problem:
$ cp /usr/share/ systemd/ tmp.mount /etc/systemd/ system/ tmp2.mount system/ local-fs. target. wants/tmp2. mount to /etc/systemd/ system/ tmp2.mount.
$ systemctl enable tmp2.mount
Created symlink from /etc/systemd/