For In Person Signer type, the Recipient Signer Na

I'm suddenly getting this error message when I try to instantiate an envelope from a template:

text: '{\r\n  "errorCode": "IN_PERSON_SIGNER_NAME_CANNOT_BE_BLANK",\r\n  "message": "For In Person Signer type, the Recipient Signer Name cannot be blank."\r\n}',

This is the code I'm using to create TemplateRoles:

  const tRole = new docusign.TemplateRole();
  tRole.setRoleName(templateRoleName);
  tRole.setName(signerName);
  tRole.setEmail(signerEmail);

  tRole.setInPersonSignerName(signerName);
  tRole.setDefaultRecipient('true');
  tRole.setClientUserId('agent');
  templateRolesList.push(tRole);

  // Create a tempalte role for each client
  // TODO: Set correct user data where appropriate instead of test data
  let count = 1;
  forEach(opts.contacts, () => {
    const clientRole = new docusign.TemplateRole();
    clientRole.setRoleName(`client${count}`);
    clientRole.setName(signerName);
    clientRole.setEmail(signerEmail);

    clientRole.setInPersonSignerName(signerName);
    clientRole.setDefaultRecipient('true');
    clientRole.setClientUserId(`client${count}`);

    templateRolesList.push(clientRole);
    count++;
  });

  console.log('templateRolesList', JSON.stringify(templateRolesList));

From that console log, I get:

[
  {
    "email": "eng@residenetwork.com",
    "roleName": "agent",
    "name": "Reside Network",
    "signingGroupId": null,
    "inPersonSignerName": "Reside Network",
    "clientUserId": "agent",
    "embeddedRecipientStartURL": null,
    "defaultRecipient": "true",
    "accessCode": null,
    "routingOrder": null,
    "emailNotification": null,
    "tabs": null
  },
  {
    "email": "eng@residenetwork.com",
    "roleName": "client1",
    "name": "Reside Network",
    "signingGroupId": null,
    "inPersonSignerName": "Reside Network",
    "clientUserId": "client1",
    "embeddedRecipientStartURL": null,
    "defaultRecipient": "true",
    "accessCode": null,
    "routingOrder": null,
    "emailNotification": null,
    "tabs": null
  }
]

In these objects, inPersonSignerName is set to "Reside Network". I don't understand why this error is appearing or what it is complaining about.

Our code has not changed (though its possible some setting in our account has).

For inPersonSigners the name and email of the user hosting the signing are required, and the name of the signer is required whereas their email is optional.

For example:

"inPersonSigners": [{
    "hostEmail": "john.doe@company.com",
    "hostName": "John Doe",
    "autoNavigation": true,
    "defaultRecipient": false,
    "signInEachLocation": false,
    "signerEmail": "optional_signer_email",
    "signerName": "Sally Doe"
}],

API Docs for inPersonSigner: https://docs.docusign.com/esign/restapi/Envelopes/EnvelopeRecipients/#inPerson