Partial Collection Failures could occur for multiple reasons. Unfortunately for Partial Collection Failure - Unknown error, the symptom is much less obvious and will require some digging to determine the root cause. I would attempt the following to rule out a possibility that it could be a DB issue with this specific device:
1. Delete it from the DNA center inventory
2. Log into the DNA CLI and run the following command while logging the console output:
-- magctl service logs -rf inventory-manager | lql
** If you receive an error that multiple inventory-manager services exist, open up another CLI session window, copy the exact name for each inventory-manager service and run the command above on each CLI session **
3. While the output is collected from the CLI sessions, please re-discover the 9800 from the DNA center appliance
4. Once successfully discovered, let the console sessions continue to collect the output from the inventory service logs until the device either goes into a Managed state or fails back into partial collection failure.
If the device goes back into partial collection failure, please upload the console output files to this discussion thread for further analysis.
