SKWarpGeometry on SKLabelNode as child of SKEffectNode flips label upside-down

I'm trying to warp an SKLabelNode as a child of SKEffectNode (documentation says you can do that), but it flips the label node upside-down before it applies the warp. This may be a bug, but before I file it, I thought I'd ask on here...

Here's my code:

func warpNode(_ node: SKEffectNode)
{
    if #available(iOS 10.0, *)
    {
        let sourcePositions: [vector_float2] =
            [
                vector_float2(0, 0),   vector_float2(0.5, 0),   vector_float2(1, 0),  //bottom row of object
                vector_float2(0, 0.5), vector_float2(0.5, 0.5), vector_float2(1, 0.5),  //middle row of object
                vector_float2(0, 1),   vector_float2(0.5, 1),   vector_float2(1, 1)  //top row of object
            ]

        let destinationPositions: [vector_float2] =
            [
                vector_float2(0, 0),   vector_float2(0.5, 0),   vector_float2(1, 0),  //bottom row of object
                vector_float2(0, 0.5), vector_float2(0.5, 0.5), vector_float2(1, 0.5),  //middle row of object
                vector_float2(0, 0.8), vector_float2(0.5, 0.8), vector_float2(1, 0.8)  //top row of object
            ]

        let warpGeometryGrid = SKWarpGeometryGrid(columns: 2, rows: 2, sourcePositions: sourcePositions, destinationPositions: destinationPositions)

        let warpGeometryGridNoWarp = SKWarpGeometryGrid(columns: 2, rows: 2)

        node.warpGeometry = warpGeometryGridNoWarp

        let warpAction = SKAction.animate(withWarps: [warpGeometryGridNoWarp, warpGeometryGrid, warpGeometryGridNoWarp], times: [0.25, 0.5, 0.75], restore: true)

        node.run(warpAction!)
    }
    else
    {
        print("Need iOS >= iOS 10 to warp!!!")
    }
}

let effectNode = SKEffectNode()
effectNode.shouldEnableEffects = true                
addChild(effectNode)

let labelNode = SKLabelNode(fontNamed: "Chalkduster")
labelNode.text = "Label"
effectNode.addChild(labelNode)

warpNode(effectNode)

This code should squish the top of the label down and then return it to its original position (as if you pushed on a ball or something), however, it flips it upside-down, then squishes the top (which is now the bottom of the word), and then returns it to its original size and position (rightside-up).

EDIT: Based on 0x141E's comment, I converted the SKLabelnode to SKTexture and added a new SKSpriteNode with that texture. If I used the warpNode function on the effectNode, it had the same effect of flipping the word upside-down and then applying the squish. However, if I used the warpNode function directly on the new SKSpriteNode, it worked properly.

New code below:

func warpNode(_ node: SKSpriteNode)
{
    if #available(iOS 10.0, *)
    {
        let sourcePositions: [vector_float2] =
            [
                vector_float2(0, 0),   vector_float2(0.5, 0),   vector_float2(1, 0),  //bottom row of object
                vector_float2(0, 0.5), vector_float2(0.5, 0.5), vector_float2(1, 0.5),  //middle row of object
                vector_float2(0, 1),   vector_float2(0.5, 1),   vector_float2(1, 1)  //top row of object
            ]

        let destinationPositions: [vector_float2] =
            [
                vector_float2(0, 0),   vector_float2(0.5, 0),   vector_float2(1, 0),  //bottom row of object
                vector_float2(0, 0.5), vector_float2(0.5, 0.5), vector_float2(1, 0.5),  //middle row of object
                vector_float2(0, 0.8), vector_float2(0.5, 0.8), vector_float2(1, 0.8)  //top row of object
            ]

        let warpGeometryGrid = SKWarpGeometryGrid(columns: 2, rows: 2, sourcePositions: sourcePositions, destinationPositions: destinationPositions)

        let warpGeometryGridNoWarp = SKWarpGeometryGrid(columns: 2, rows: 2)

        node.warpGeometry = warpGeometryGridNoWarp

        let warpAction = SKAction.animate(withWarps: [warpGeometryGridNoWarp, warpGeometryGrid, warpGeometryGridNoWarp], times: [0.25, 0.5, 0.75], restore: true)

        node.run(warpAction!)
    }
    else
    {
        print("Need iOS >= iOS 10 to warp!!!")
    }
}

let labelNode = SKLabelNode(fontNamed: "Chalkduster")
labelNode.text = "Label"

let labelNodeTexture = SKView().texture(from: labelNode)! 
let labelNodeSprite = SKSpriteNode(texture: labelNodeTexture)

addChild(labelNodeSprite)

warpNode(labelNodeSprite)

I just eliminated the whole effectNode part of the code and added the new sprite and did the warp on that.

Edited my question as the answer based on 0x141E's comment.