This article explains how to troubleshoot any one particular route despite being advertised from peer is not received at local device in BGP.

Kindly check the specific prefix advertisements from both the peers by below command :

show route x.x.x.x extensive

show route x.x.x.x/x<IP prefix> receive-protocol bgp x.x.x.x <Neighbour IP> extensive --- On local device

show route x.x.x.x/x<IP prefix> advertising-protocol bgp x.x.x.x <Neighbour IP> extensive --- On remote device

Need to follow the below troubleshooting steps ,

1. First find out the prefix origin point we are receiving the routes from EBGP peer via the RR in the network.
2. At remote end x.x.x.x/x prefix is learned from some external network with private AS number xxxx.
3. Check the export policies towards all external EBGP peers in vrf where this particular prefix is being advertised in a particular policy.
4. But despite that export policy in show route advertise-protocol bgp towards any of the External peers couldn't see this prefix advertised.
5. Check the route hidden table which for this prefix and see the reason for hidden
6. Check the policy option which is used to reject Private AS numbers & found that particular AS number xxxx is being called in that list & rejected in export policy.
7. Try to deactivate the specific AS-number-list & immediately routes x.x.x.x/x will advertise to all external peers.
8. It was configuration issue in customer environment due to which router was not advertising the route

Note: However this solution was useful for customer specific network environment only.