https://docs.vmware.com/en/VMware-SD-WAN/5.2/VMware-SD-WAN-Administration-Guide/GUID-AA2A434D-A249-4...
The link above describes how to set up VRRP, as well as some of the conditions for it to work.
But for the description of problem you describe, it sounds like an issue with ARP, and that the switch is not able to get the correct MAC address for the VRRP VIP, so it will not be able to ping it. Did you check the ARP table to see what the value of the MAC address associated with the VRRP VIP is?
Also, have you verified that VRRP is operating between the VCE and the AVPN router?