Does anyone know how the option of

item filter

under

sublist fields

from a

form

works? On the help it just says that this option filters so some items are not being shown, but from some tests I did, if the item is not shown it doesn’t even let the item to be set (I tried to do that via script but it throws an error saying

Invalid item reference key 3129678 for subsidiary 3.

) And when I deactivated the option, the item was set without any issues.

If I understand correctly, that filters the item dropdown on the UI based on the criteria. It removes certain items from being selected in the UI. So if the User were to add Item, they can only select what is being shown. NS might be applying the same filters when you are setting the items via script, that is probably why you are getting the error. This is probably done so that you have the same result/behavior whether the record is created manually or via script.