Why my flatlist horizontal footer is not at the bottom?

I use flatlist horizontal and want to add a footer at the bottom, but the footer is on the top. Why ?

    <Modalize
      ref={ref}
      modalHeight={175}
      modalStyle={{  padding: 8 }}
      flatListProps={{
        data: addAllColorsInArrayWithoutKeys(),
        style: {
          padding: 0,
        },
        renderItem: renderItem,
        horizontal: true,
        keyExtractor: (item, i) => i.toString(),
        showsVerticalScrollIndicator: false,
        ListFooterComponentStyle: {flex:1},
        ListFooterComponent: <View style={{flex: 1}}><Text>Footer</Text></View>
        ,
        scrollEventThrottle: 16,
        maxToRenderPerBatch: 2,
        keyboardShouldPersistTaps: 'handled',
        initialNumToRender: 4,
        updateCellsBatchingPeriod: 200,
        getItemLayout: (data, index) => ({ length: 40, offset: 40 * index, index }),
        contentContainerStyle: {
          justifyContent: 'center',
          alignItems: 'center',
          paddingHorizontal: 20,
          flexGrow: 1
        }
      }}
    />

How can make it at the bottom ?