Changing the Test Plan field to a Required field doesn´t make it required when creating a Test Execution

Description
If you change the Test Plan Custom Field from Optional to Required field, when creating a Test Execution it should be mandatory to fill that field with some data.

How to reproduce

1. Go to the Field Configuration of the Project and search by Test Plan;
2. Change it to Required field;
   
3. Create a Test Execution issue;
4. Don´t fill the Test Plan field with data and click on Create;

Actual result/Attachments
The Test Plan field shows the star indicating that is a Required field but you can create the issue without filling any data on it.

Expected result
It should not let you create the issue without data on the Test Plan field and pop up a warning saying it´s missing a required field.

Version

• 5.1.3