Display MoreSSH in and run:
connmanctl
agent on
scan wifi
services
connect wpa_blah_blah_psk
Enter the password when prompted. If this works (using connman's own dbus agent) the issue is in LE settings code. If it barfs here, the issue is somewhere else.
Thank you, this worked. My scenario was the same as crushedy's. I changed the SSID of my network and wasn't able to update the settings in LE Config. There must be a bug in the Configuration addon.