Xfce4-session preventing /tmp from getting unmounted when shutting down system

When I try to shut down my system, what happens is that it’ll show that the PC failed to unmount /tmp. However, when other applications are not running and I attempt a shutdown, the only process that is using /tmp is xfce4-session. This problem started appearing after I updated my nvidia drivers via dkms and did “pacman -Syu”.