The documentation for a combo box in https://api.libreoffice.org/docs/idl/ref/servicecom_1_1sun_1_1star_1_1form_1_1component_1_1DatabaseComboBox.html#a2f99ac4d478a97752dfe0fac8cf8b232 regarding com::sun::star::form::ListSourceType ListSourceType is of little value (or even none). It says: specifies the kind of list source. Note: A value of com::sun::star::form::ListSourceType::VALUELIST is not valid for a combo box. It won't be rejected when setting it, but controls will usually ignore it and leave the list empty. But obviously the values 1 to 5 of the named list are used when creating combo boxes in a form: the names displayed and the integer values shown afterwards when inspecting the combo box do coincide. And anyway: a positive statement which values might be used is necessary.
Moving to NEW