Same here. Was working a few hours ago.
I am using the Alexa media service custom plugin but until I read your post I didn’t realize it was just node red. I’m on 86.1
I encountered the same error with some of my notifications, but not all of them. Notifications after a call service node stopped worked, but notifications after a state node or switch node worked fine.
I was able to get the notifications following a call service node to work by modifying the preceding call service node and setting the output location to none. So far no ill effects.