It appears that a lot of Echo devices were not responding today.
At about 8pm (Pacific time), my Echoes will light up when I say "Alexa" but it will ignore everything I said after that.
It seems to have fixed itself at about 11:30pm.
Possibly Amazon servers were having problems again.
I have two echo dots and both are not working. It's knows it's name but won't answer Any body else having this problem today?