PCG Graph on 2x2 Landscape incorrectly displays weight on paint layers

In my example picture I have "Grass" set as the target attribute area but the debug cubes are appearing on the dirt and snow as well. 

This only happens when the landscape subsections are set to 2x2

This is not a regression as certain steps cannot be done in 5.1

1. Create a new Open World level
2. Create a landscape with 2x2 subsections and apply Landscape Material
3. Make paint layers weight blended and paint them on the landscape
4. Add a PCG volume and create a PCG graph
5. In PCG graph create Surface Sampler node from the Landscape Pin in the Input node
6. From Surface Sampler node create a Point Filter node
7. Check "Use constant threshold"
8. In Target Attribute put the name of one of the paint layers (Grass, Snow, Dirt)
9. Set Threshold type to Float and put Float value at 0 > turn on Debug in the details panel

Expected Results: The debug cubes should only appear in the Target Attribute area

Actual Results: The debug cubes will appear in strange patterns 

UE-187192 "PCG Graph on 2x2 Landscape incorrectly displays weight on paint layers"