The feature Flow Message Queue allows you to see number of messages in the queue for each of your flow steps:
Please Note: The Flow Queues are only available for actively running flows.
To access navigate to Executions, select any active execution:
Then look for the Flow Queues menu link along with the Download Logs and View Flow links like in the picture below:
To access navigate to Dashboard, select any active flow and look for the Flow Queues menu link along with the Download Logs and View Flow links like in the picture below:
To access navigate to Flows, select any active flow, click to cogwheel and select Flow Queues:
You can also access the queue information using the /v2/stats/queues/FLOW_ID
API endpoint. More information is available from the API reference documentation.