Sub-Types display internal name where display name should be (Object Details page)

Here's a new one... WC11 M030 relatively new installation.

Have created sub-types for a number of Data Types... we can keep it to Documents for the purpose of this question.  Display Name has been set when creating in the Type and Attribute Manager Utility, but on Object Details Page the internal name {com.mycompany.objSubType} is displayed.

Any clues?