No flows are populating in Aria Operations for Networks GUI.
You have added third party devices like Cisco USSM, Cisco Nexus 9K switches, Arista switches, etc, as data sources in the GUI.
You have configured netflow and/or sflow to export to the Collector.
In Settings > Data Sources and Accounts you don't see any errors and you see that the Last Metric Collection and Last Configuration Collection has a time listed in minutes (e.g. 5 min, 6 min, 9 min, 11 min, etc.) but in the Flows column "--" displays as in the screenshot below:
Aria Operations for Networks 6.13.0
Aria Operations for Networks 6.14.0
Aria Operations for Networks 6.14.1
This is expected behavior.
Third party device flows (NetFlow, sFlow) are not collected by the data source configured for metrics and configuration data.
Instead non-VMware (i.e. not vCenter or NSX) flows must be configured as a Physical Flow Collector (Netflow, sFlow) data source that is configured with a Collector VM appliance that is dedicated for flows from non-VMware / 3rd Party (often referred to as "Physical") devices.
To receive Netflow or sFlow from a third party "physical" device, you must have three elements:
Use the following steps to complete the three elements listed above:
Note: You may need to wait for a couple of hours (at max 2-3 hours) for each device for the flow number information to be seen in Aria Operations for Networks.
Reference technical documentation for more details: