Luoshuang's GPULightmass

Does anyone know why I’m getting spots in my shadows? These are my bake settings:

[DevOptions.GPULightmass]
NumPrimaryGISamples=128
NumSecondaryGISamples=32
FireflyClampingThreshold=900000.0

Lighting Quality is set to Production.

Lightmass settings:
Static Lighting Level Scale: 0.1
Indirect Lighting Bounces: 100
Sky Lighting Bounces: 20
Lighting Smoothness: 1
Diffuse Boost: 2

Engine version: 4.20.3

Here’s the issue: