A device for blocking ejection of crop material from an auger platform of an agricultural harvester features a shield for lying along an axial direction defined by a rotational axis of an auger of the auger platform reaching forwardly over the auger, and a flexible guard attached to the shield to run along the width dimension adjacent the free edge of the shield to hang downward therefrom with the shield in the operational position. A floating connection arranged between the shield and one or more shield mounts attachment the same to the auger platform allow floating of the shield upwardly out of a normal operational position, which is user adjustable. A flexible seal maintains a sealed condition between the shield and the auger platform throughout movement of the shield and in each of several user-selectable operating positions.