Issue Summary

When creating an issue from the + Create link on a board, creation will fail silently if the default assignee does NOT have ASSIGNABLE permission OR Unassigned issues are turned off.

An error message appears in the network response but nothing appears in the UI.

Steps to Reproduce

1. Go to company-managed Jira Work Management board
2. Ensure that default assignee is "Project lead"
3. Ensure that default assignee does not have "Assignable user" permissions, or is inactive
4. Click + Create
5. Type a Summary and click Create button:
   
6. Modal with no vertical scroll appears. Click Create on that:
   
7. Observe Spinner appears on button and then disappears. No error messages in UI I think because the Assignee field doesn't appear on the toaster. If you go to the network tab you will see following error:

   {
       "errorMessages": [],
       "errors": {
           "assignee": "The default assignee does NOT have ASSIGNABLE permission OR Unassigned issues are turned off."
       }
   }

8. Note, if you create the issue using the top nav blue Create button, the modal shows the Assignee field so you can see the inline error:
   

This does not appear in the little side modal (toaster?) that appears when you do inline Create from board.

Modal pops up. Click Create (again!):

Expected Results

Errors should appear in clear UI warning.

Actual Results

Errors appear only in Network response.

Workaround

To see the error message in the UI, Create issues using the blue Create button:

Steps to troubleshoot underlying error: https://confluence.atlassian.com/jirakb/agents-and-customers-are-not-able-to-raise-requests-in-a-jsm-project-via-any-channel-the-default-assignee-does-not-have-assignable-permission-or-unassigned-issues-are-turned-off-1189507485.html