OneView 8.6 Not Sending Expected REST Event from iLO,While OV 6.6 Functions Properly

[HPESeven]

Dear all, 
Good day,
I have encountered a strange issue and wonder if anyone else has experienced it.
The specific situation is as follows:
When adding the server to the OV6.6 instance, everything is normal. However, adding it to OV8.6 (or 8.4) results in a warning:
"HPE OneView did not receive an expected REST event notification from the server’s iLO. It is possible that event notifications from the server are not reaching OneView, resulting in impaired monitoring and management capabilities for that server. The following may be impacted:
• Firmware update using Smart Update Tools (SUT).
• Inventory updates (CPU, memory, disks, adapters, firmware/software and others).
• Local storage configuration.
• Detection of other changes such as UID light status and power state (which can affect profile apply performance).
Active
Resolution
Follow the steps provided below until this alert has cleared.
• Ensure that both the outbound and inbound TCP port 443 are not blocked by a firewall. Both outbound (HPE OneView to iLO) and inbound (iLO t must be enabled for REST events to be successfully received in HPE OneView.
• Refresh the server hardware after enabling the TCP port 443.
• If refreshing the server hardware did not clear the alert, reset the iLO and then refresh the server hardware again."

It's worth mentioning that I've tried installing OV8.6 using the IP of OV6.6, and it still doesn't work.
I believe this can largely rule out the firewall as the cause. 
Is there any advice for further troubleshooting that you can recommend?

Thanks

Seven

[Kashyap02]

Hello.

What servers are added to OV ?
Are the ILO on them are at latest firmware ?
Are the ports open in the firewall for 2 way communication ?

Recommendations: 
1. update the ILO to latest firmware 
2. Restart the AMS service. 
3. Reset the ILO
4. Clear the RestAPI state from ILO CLI. 

> SSH to ILO CLI using admin credentials.
> issue command  oemhp_clearRESTAPIstate
> Wait for ILO reset to complete
> Refresh the server in OV and verify.