It isn't possible to create a Story within an Epic if there is a validator requiring Epic Link not be empty

Summary

When creating a Story within an Epic in Portfolio, if there is the following validator on the create transition:

If a value for field Epic Link is not provided during the transition, show the following error: Epic LInk must be filled-in.

The Story creation will fail. In this case with "Epic LInk must be filled-in.":

The issue should be resolved by setting the Epic Link field as required in the field configuration. However, it isn't possible to do so since the said field is LOCKED.

Environment

Cloud - JIRA v1000.620.0

Steps to Reproduce

1. Set a Field Required Validator to the Create transition for Stories.
2. Within a plan in Portfolio, create a Story under an Epic.
3. Commit the changes
4. You'll be prompted the Set required fields screen. However, the Epic Link isn't listed.

Expected Results

Since the Story is being created from within an Epic, the Epic Link field shouldn't be required to be filled-in.

Actual Results

Story creation fails due to the validator and not having the possibility to fill in the Epic Link field.

Workaround

Remove validator, use required field instead.