NetworkManager not able to manage WWAN devices in 18.04 server

Installed a 18.04 server image, and installed NetworkManager.

NetworkManager comes with a "/usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf" file where it speciefies that all devices are by default unmanaged except for types "wifi" and "wwan".

Now, the problem is that the filter should apply to "gsm" or "cdma" types, not "wwan".

E.g.:
  [keyfile]
  unmanaged-devices=*,except:type:wifi,except:type:gsm,except:type:cdma

Before the change:
$ nmcli d
DEVICE TYPE STATE CONNECTION
wlan0 wifi connected Bumbu
eth0 ethernet unmanaged --
cdc-wdm0 gsm unmanaged --
lo loopback unmanaged --

After the change:
$ nmcli d
DEVICE TYPE STATE CONNECTION
wlan0 wifi connected Bumbu
cdc-wdm0 gsm connected cell
eth0 ethernet unmanaged --
lo loopback unmanaged --