In a VCS configuration, we have physical interfaces/IPs and service group logical interfaces/IPs. When testing client (6.5.x and 7.x) connectivity from master server (first entry in bp.conf) using bptestbpcd, initial connections to the logical IPs fails; however, if we then run a connectivity test to the physical interface it works, and all subsequent tests to the logicals works just fine. It's as if the connection to the physical "primes" the server for successful logical interface connections.
After a given amount of time (we haven't established exactly how long yet), this condition resets itself and we must "prime" again....leading me to believe there is a timeout associated with this. Needless to say, when our backup jobs kick off for the logical interfaces, it fails too.