One of the features that was handy with Netflix on the FireTV was the ability to Alexa to start an episode over via the commands “Alexa, Play from the beginning” or “Alexa, start over”.
Though this feature used to work with Netflix, sometime between January of 2019 and February of 2019 Alexa began responding with “Start over is not supported.”.
At this time there is no known fix for the issue, as soon as one becomes available this post will be updated.