VAULT_BALANCE_UPDATE (V2 - Webhook)

I’ve joined the Early Access Program to use the Refresh Vault Asset Balance V2 Webhook (VAULT_BALANCE_UPDATE). However, I haven’t been able to find any official documentation on how to use the Early Access features.

I’m trying to test it, but I keep getting a 401 Unauthorized error. I’ve already added the Webhook V2 URL under Settings > General, and I’m currently using Webhook V1 successfully.

Could you please help me understand how to properly use and test the V2 webhook for VAULT_BALANCE_UPDATE?