US12345 an unexpected error occurred: Validation error: HierarchicalRequirement.CustomField Value [ Value1 ] for field [ CustomField ] is invalid. Valid values are: {[Value2, Value3, Value4]}
It is possible to simply readd the field into the custom field value list. A project admin or possibly workspace admin will need to make this modification.
It will be necessary to ensure that the definition is readded in the correct artifact type. By default the field edited will only be applicable to defects so it may be necessary to change the "type" and modify a user story field, for example.