Kibana alerts on Resolution

I can read in the documentation:

Kibana alerts tracks and persists the state of each detected condition through alert instances . This makes it possible to mute and throttle individual instances, and detect changes in state such as resolution.

I have a Slack connector receiving Kibana alerts in a Firing state. Nevertheless I do not receive anything when alerts are resolved. Is this feature supported ?

Not yet. It should be available in an upcoming 7.x minor release of Kibana.