I have a motion sensor plugged into the bottom of an echo flex.
The motion sensor triggers a helper in Home Assistant which in turn triggers an automation to turn on the light.
In the past few weeks, this automation occasionally fails, and although the motion sensor reports movement to the alexa app, it doesn’t trigger the helper in home assistant.
Voice commands to a different echo device also fail to work.
I have found that signing out of Nabu Casa, and then immediately signing back in again, fixes both of these problems.
It seems as though this procedure re-authenticates with Amazon.
I have no issues accessing Home Assistant away from home.
I found this “fix” here