This issue has been resolved in more than one way.
The first thing to check is the rights of the BBIS account linked to the CRM application user editing the Marketing effort. Make sure the account belongs to a Role whose Security Assignment ties it to a task group with Full Rights to Template Tasks in the Role's Task Group (Site Tasks):
- Edit BBIS User in Users & Security > users
- Identify Role related to BBIS Email tasks
- In the Admin toolbar, Click Users & Security > Roles
- Edit Role identified in step 2 and select the Security Assignments tab
- Identify the Task group that includes "(Site tasks)"
- In the Admin toolbar, Click Users & Security > Task Groups
- Edit the Task Group identified in step 5
- Scroll to the Email Security node
- Ensure that "Full Rights" is selected under the "Email template tasks" node
- Click Save
If you encounter 401 errors in logs or traces, this could be an issue with load-balancer. For each BBIS node, edit the local Hosts file and add an entry for the BBIS & BBEC load balancer domains that are running locally to keep all internal API http calls local on the node.