Webhook validation works on 'orders/create' but not on 'subscription_contracts/create'

[RaiselCast]

I'm using the following sentence to validate a Webhook:

  const {valid}= await shopify.webhooks.validate({

    rawBody: JSON.stringify(req.body),

    rawRequest: req,

    rawResponse: res,

  });

It works as expected when a ORDERS/CREATE webhook is triggered, but in the case of 'SUBSCRIPTION_CONTRACTS/CREATE' it always return FALSE.

Any idea about what's happening here?

Thanks in advance!