Picker Controls with Multiple Values
When you have a picker control that is set to allow multiple values only the identifier property is populated. The other properties are blank.
For example if you have a picker bound to UMUser with the identifier set to FQN. When you enter a single user all the properties are available (i.e. name/display name/manager etc). When you add more than 1 user to this picker the name/display name/manager etc) are simply blank.
The use case here could be that you want to display the managers for the users selected in the picker on the form in a semi-colon delimited list.
Currently you have to iterate through the items in the picker control by using form rules or workflow loop shapes to populate that information iteratively.