When an edge BGP neighbor is flapping, not all the neighbor state changes will show up in the VCO events for that edge.
In the case of a gateway BGP peer, the "Related State Change Events" on the "BGP Gateway Neighbor State" may not reflect the latest BGP flap, but the Up/Down time will indicate the peer state has changed more recently.
This is due to the way we currently identify neighbor state changes and send them to the VCO:
This means any BGP flap that happens within that 60 seconds does not show up on the VCO. If for example the neighbor state was Established, and then was at another state like Active or Connect during the next 60-second poll, that change would show up as an event in the VCO.
This is the way we currently report BGP neighbor state events in the VCO.
If there is any interest in submitting an enhancement request to improve how we do this, please speak with your account manager or solutions engineer with Broadcom SD-WAN.