Clean install ubuntu 16.04 cannot connect to wifi using NetworkManager, but nmtui works
I have been having the same issue, While not a fix, I found that restarting the network manager works. I have included the instructions to do this below.
From the command line
Stopping Network Manager
sudo /etc/init.d/network-manager stop
Starting Network Manager
sudo /etc/init.d/network-manager start
I solved the problem by typing my password into a document, and then copying and pasting it into the password field.
For some reason the connection was timing out before I could type my (long) password in but not giving me any messages about it.