Can't start polkit-mate-authentication-agent

I'm using Mate on Parabola GNU/Linux (based on Arch). I have the polkit-mate-authentication-agent installed and it is supposed to be autostarting on login to the desktop; however, it doesn't seem to be starting, either automatically or manually. In my ~/.xsession-errors file, I see the following error: (polkit-mate-authentication-agent-1:24207): dbind-WARNING **: 07:13:53.904: Couldn't register with accessibility bus: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken. Cannot register authentication agent: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: Cannot determine user of subject I see a very similar error if I try to start it from the terminal, either as a regular user or as root. The errors file also shows dbind warnings for a lot of other packages - I don't know if that has anything to do with it. I am using openrc, not systemd. The problem seems similar to this existing question; however, starting manually seems to work there, so the underlying problem may not be the same: https://unix.stackexchange.com/q/303530/257802 Any ideas or suggestions? **Edit:** The output of ps -Af | grep dbus seems to show dbus is running and a daemon is owned by the logged-in user: $ ps -Af | grep dbus dbus 1332 1 0 Mar21 ? 00:00:14 /usr/bin/dbus-daemon --system john 15835 26842 0 10:18 pts/0 00:00:00 grep --color=auto dbus lightdm 24087 1 0 07:13 ? 00:00:00 dbus-launch --autolaunch 91d1384971b9deaa251b73355e5436ad --binary-syntax --close-stderr lightdm 24088 1 0 07:13 ? 00:00:00 /usr/bin/dbus-daemon --syslog-only --fork --print-pid 5 --print-address 7 --session lightdm 24096 24090 0 07:13 ? 00:00:00 /usr/bin/dbus-daemon --config-file=/usr/share/defaults/at-spi2/accessibility.conf --nofork --print-address 3 john 24117 1 0 07:13 ? 00:00:00 dbus-launch --exit-with-session mate-session john 24118 1 0 07:13 ? 00:00:00 /usr/bin/dbus-daemon --syslog --fork --print-pid 5 --print-address 7 --session dbus also seems to be running and working, according to the output of busctl. I also tried installing the Gnome authentication agent (polkit-gnome) and I get the exact same error when I try to run it from the terminal.