Unable to see the BGP down alert on VCF Operations for Networks which is seen on NSX alerts tab seen below.
VCF Operations for Networks
Unable to see BGP down alerts on NSX on VCF Operations for Networks because the Alert from External for NSX is disabled under Settings > Alerts and Notification > Alert Definitions > Others
Enable the 'System Alerts from NSX-T' under Alerts from external sources as seen below on VCF Operations for Networks: