Type::getName() is currently not implemented by some FieldTypes, such as Relation or Selection. This has been reported (EZP-24640) as a bug by some users.

Enabling this has different requirements depending on the FieldType. Selection::getName() requires access to the FieldDefinition, while Relation would need to load the related Content item(s) to get its name.

getName() must be implemented for FieldTypes that make sense as name elements.