NSX-T manager > Inventory tab > Virtual Machines you can confirm the Edge VM does not exist.Edge VM Present in NSX Inventory Not Present in vCenter".The issue occurred due to a stale entry related to the Edge VM in the Corfu database table following its deletion.
This issue is resolved in VMware NSX 4.2.0 and later, available at Broadcom downloads.
If you are having difficulty finding and downloading software, please review the Download Broadcom products and software KB.
Workaround:
Restart the proton service on each manager node to ensure the monitoring cache is cleared.
service proton restart