I confirm, this still exists in Debian 10 (Buster). Debian Desktop GNOME3...xRDP package seems to be missing PolicyKit configuration files for GNOME3 shell. I also wish to add that org.freedesktop.packagekit.system-sources-refresh should be added to this list. There are also other PolicyKit configurations related to using GNOME Control Center.
Additionally, GNOME Keyring isn't getting unlocked with PAM. sudo bash -c "cat > /etc/pam.d/xrdp-sesman" <<EOF #%PAM-1.0 @include common-auth auth optional pam_gnome_keyring.so @include common-account @include common-session session optional pam_gnome_keyring.so auto_start @include common-password EOF
