I am just here to report a bug with the Add Data Widget (we are on Portal 10.6.1).
We can't add data on our webapp because the add data widget calls the property "displayField" as a function. Or, the error is clear : "d.displayField is not a function"
(Solution : we deleted the displayField and it's ok again)
(not sure writting here is the best thing to do tho. Should I send an email to the support ?)
Have a nice day !