Cannot create subtasks if there is a required field on the new JIRA issue view.

Problem Description

Unable to create subtasks on the new JIRA issue view if there is a required field.
Error "Wait a few moments, than give it another try."

Also, the button to quick add sub-task is not shown.

Steps to reproduce

1. Ensure you are 'Experiencing the new Jira' aka ADG3
2. Set up your project to the have Assignee field as required while creating a new Subtask OR the Summary field not included in the Create/Edit Issue screen of the subtask
3. Access a board.
4. Create a new Story.
5. Select the Story on your board.
6. Try to create a new sub-task via the new Jira issue view 

Expected Result

A pop up to enter the issue's required fields should appear.

Actual Result

Error "Wait a few moments, than give it another try" is shown or the option to create sub-task is not available.

Workaround

1. Remove the required field
   or
2. Open the issue in JIRA, outside the board view, there you will be able to create a new Subtask.

OR

Include the Summary field in the Create/Edit Issue screen of the subtask