Can't create new Reference to Model DataType

[joe-crawford]

Description

When creating a Reference to Model DataType, no model selection box/menu appears.

Steps to reproduce

• Create a new DataType in a DataModel and select 'Reference to Model'
• No option to select a referenced Model appears

Screenshots

Environment

Latest develop of mdm-ui and mdm-core

Desktop

macOS Safari

[joe-crawford]

Was also present on develop before PR#836, but appeared slightly differently.