That is strange. I wish we knew what was going on...
Once again I was able to successfully log back into my Amazon account using @gabriele's Alexa-Cookie NodeJS server. I then copied the "Alexa cookie refresh options" into the App in HUbitat, clicked the "Force Refresh Now?" to on, and five minutes later everything is back to working again.
So, I know the Alexa-Cookie NodeJS server is capable of getting a cookie and sending it to Hubitat successfully. It just appears that after a few days, it cannot get another new cookie.