There are 2 problems :

(a) When a network , subnet , router is created and VM is booted , ARP RESPONDER table (81) contains router gateway MAC in eth_src field.
When router is associated to BGPVPN , eth_src filed in table=81 , entry is replaced with VM's connected MAC address.

It leads to ping failures.

(b) A network , subnet , router is created and VM is booted. MY MAC table (19) contains router gateway MAC address . When the router is associated with BGPVPN , VM's MAC address is added into MY MAC table (19) which is not required.
When router is disassociated , VM's MAC address entry remains in table=19 (stale entry)