GPU Lightmass banding

Hi there!

I’m using GPU Lightmass with Ray Tracing reflections and translucency. My meshes are all red (in terms of lightmass density), and this specific wall has an overriden Light map res of 2048.

The Compress Lightmaps option is disabled in the GPU Lightmass menu and in the World Settings.

What can I do to avoid banding?