When querying the data outside of the NSX-T app do you need to specify an index in your search? If you are normally doing this anyway, try and search without the index and see if you are still receiving results.
If not, you'll need to add the index as a default index for the user group that will be using the NSX-T Splunk app.
Default indexes can be set under: Settings > Access Controls > Roles, and clicking on the role you wish to edit. The specifics of these menus will change a little between versions.
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