Rules of this sort, whether
udev are no longer necessary if you have an active session under systemd/logind. Originally, rules of this sort were a workaround for non-consolekit sessions, but now Arch has moved to systemd they are no longer necessary and are more likely to inhibit correct automounting behaviour rather than assist it.
You can check that you have an active session with:
loginctl show-session $XDG_SESSION_ID
which should show amongst its output:
If this doesn't show, and you are not using a display manager, you need to ensure that when you start
X your session is preserved—so
X must be run on the same TTY where login occurred. See this entry on the Arch Wiki.