Check in order:
1. Is the Metricool integration active under Settings → Integrations?
2. Does the client have a valid Metricool Blog ID in the profile?
3. Are there actually posts scheduled in Metricool for the selected period?
4. Has the right filter (client, view) not filtered everything out?
Posts are pulled from Metricool in real time — if they are in Metricool, they should also be here.