When using the bulk editor, some properties under 'Property Types' that were previously selected will disappear after adding additional objects in 'Object Types'.
For example if you select 'Attributes' under 'Object Types', and then 'Name' and 'Null Option' under 'Property Types' and then switch back to 'Object Types' to add additional objects such as "Entities", when you switch back to the Property Types tab again, many of the properties including null option which was was previously selected are no longer available in this list.
This is because only properties that are common to all the selected object types (specified on the Object Types page) will be shown shown. In the example above, the 'Null Option' is a property of 'Attributes' but not that of 'Entities'. However 'Name' is a property of both 'Attributes' and 'Entities', which is why 'Name' still shows under the 'Property Types' after 'Entities' is selected in 'Object Types'.