Getting ACCOUNT_NOT_AUTHORIZED_FOR_ENVELOPE when using embedded signing with a different user

Hello,

I am experiencing an issue with the embedded signing flow and would appreciate any guidance.

Scenario:
We create envelopes using a system administrator account via the eSignature REST API, then attempt to generate an embedded signing URL (CreateRecipientView) while authenticated as a different DocuSign user.

Error received when calling CreateRecipientView:

{
  "errorCode": "ACCOUNT_NOT_AUTHORIZED_FOR_ENVELOPE",
  "message": "This account is not authorized to access the requested envelope."
}

What we have confirmed so far:

• The envelope is successfully created by the admin account.
• The accountId used in the CreateRecipientView endpoint matches the one used during envelope creation.
• recipientId and clientUserId are set in the CreateEnvelope request.
• The signer email/name matches the recipient definition.
• We are using a different authenticated DocuSign user (different access token) when calling CreateRecipientView.

Questions:

1. Does CreateRecipientView need to be called using the same DocuSign user (access token) that created or owns the envelope, even if the embedded signer is a different recipient?
2. If another user within the same DocuSign account calls CreateRecipientView, are additional permissions or shared access settings required?
3. Are there other common causes of ACCOUNT_NOT_AUTHORIZED_FOR_ENVELOPE that we should check?

Any advice or documentation references would be greatly appreciated.

Thank you.