All, Amazon is having some serious backend issues, effecting a lot of their services. Unfortunately, Alexa appears to be one of them. Discovery messages aren't getting to Indigo at all, but reflectors are otherwise up and running, so it's pretty clear Alexa is out of commission for the moment. We'll just have to wait for Amazon to get their system issues fixed and hope that happens soon.
I guess it's a good thing Indigo is locally hosted rather than hosted in the cloud...