Issue Summary

When setting 'Allow unassigned issues' to 'OFF' you instruct the system to not allow to create issues when there is no assignee associated with the issue.
When creating next-gen service desk projects you can set an automation rule to set a default assignee

When 'Allow unassigned issues' to 'ON' it assigns the selected default assignee

However, when this setting is set to 'OFF', the system does not recognise the default assignee and does not allow the customer to raise an issue via the portal.

Steps to Reproduce

1. Turn OFF "Allow Unassigned Issues" under global settings
2. Go to your next-gen Service Desk project
3. Check that you have a default assignee on the project
4. Raise a request via the customer portal

Expected Results

Issue should be created with the default assignee picking project lead as a default assignee.

Actual Results

you will get an error message:
Couldn't send request
This form contains a hidden field that does not have a valid default value configured

Workaround

Setting 'Allow unassigned issues' to 'ON'