Thr attached script is a work around (tested on 12.04LTS) put into /etc/init.d as mm_monitor and execute
$ sudo uptate-rc.d mm_monitor defaults
The script run as a daemon ensuring that nmcli nm wwan on is called whenever modem manager adds a device. Beside solving the bug as described it also ensure that auto-connect system-accessible WWAN devices are connected on startup (which was my original problem)
Thr attached script is a work around (tested on 12.04LTS) put into /etc/init.d as mm_monitor and execute
$ sudo uptate-rc.d mm_monitor defaults
The script run as a daemon ensuring that nmcli nm wwan on is called whenever modem manager adds a device. Beside solving the bug as described it also ensure that auto-connect system-accessible WWAN devices are connected on startup (which was my original problem)
Hoping it helps
TH