Cusom Lwc in Flow not returning value, summer 20
Ok, I have also been struggle with this issue for today. I have two lwc components embedded in lightning flow. Both of them use "FlowAttributeChangeEvent" to communicate value back to the flow. After update to summer 20 on my scratch org both of them do not updated output attribute correctly. I fixed one of them by increase lwc api version from 47.0 to 49.0. However for the other one I still face the issue that property does not get update and here is the flow config:
What I found is that if I change "Set component visibilty" to always visible then my attribute almost always populated with the "FlowAttributeChangeEvent". If I have set the "Set component visibilty" with conditions it seems like the flow failed on retrieving values from "FlowAttributeChangeEvent". I feel this is a salesforce bug on their flow after the upgrade. But I cannot find any issue logged on community about this behaviour.
My walk around for now is to stop use "Set component visibilty" and use decision is route between two screens and one of the screen always have the lwc component show.
I have been having the same issue today. Finally solved it by firing the FlowAttributeChangeEvent but outside the getter...before firing my FlowNavigationNextEvent.