When a custom field which is not present on the create issue screen is marked required, new defects cannot be created. When attempting to create the defect, it is rejected with the message "<your custom field> is required"
I have created a custom field, called reviewer, which is only present on the resolve screen. In the field configuration, the reviewer is marked required. Now when attempting to create a defect, the defect is rejected because the reviewer is not present, but the reviewer field is not present on the create screen. The check for the field being required should only happen on screens that contain the custom field.