Type=dbus systemd services toggle between active and inactive by "systemctl isolate"

Issue

• dbus-broker.service becomes inactive after the first "systemctl isolate"
• When dbus-broker.service is (re)started, NetworkManager.service becomes inactive if it is already up, and becomes active if it is down.
• If runlevel is changed odd number of times (once, thrice, etc...), NetworkManager service stops.
• This problem occurs when runlevel is changed from 3 to 5, or 5 to 3.