The following configuration breaks labeling interface - one can not assign a label to a rectangle:

<View>
  <RectangleLabels name="label" toName="image">
    <Label value="Airplane" background="green"/>
    <Label value="Car" background="blue"/>
  </RectangleLabels>
  <Image name="image" value="$image" grid="true" gridSize="40"/>
</View>

If you remove grid="true" gridSize="40" from Image tag then you can assign a label to a rectangle.

Environment (please complete the following information):

• Label Studio Version == 1.6