SUMO-269514 | Apoorv | Add Index filter Note to EventHub docs

Author: Apoorvkudesia-sumologic

docs/integrations/microsoft-azure/azure-event-hubs.md

@@ -183,6 +183,10 @@ import AppUninstall from '../../reuse/apps/app-uninstall.md';
 
 ## Troubleshooting
 
+:::note
+Index Filter: If an invalid or non‑existent index is provided in the dashboard filters, an error is returned instead of a 'No Data to Display' message.
+:::
+
 ### Metrics collection via Azure Metrics Source
 
 To troubleshoot metrics collection via Azure Metrics Source, follow the instructions in [Troubleshooting Azure Metrics Source](/docs/send-data/hosted-collectors/microsoft-source/azure-metrics-source/#troubleshooting).