I baked the light on the CPU in shadow mask mode and after that all the lightmaps turned completely black. Before that, I had shadows disabled and everything worked, but after I selected them, I got this result.
More than 160 error reasons were also displayed in the console:
[PathTracer] InitializeLightmapData job failed with extension: 830ab86104c35ac903515080b3632d81 with exit code 2.
It was with disabled shadows, but then everything worked.
From the second screenshot you’ve attached, it’s evident that there’s baked output in the scene, but it’s very dark. You might be exceeding overlapping light limit in shadowmask. Or, you’d simply need to increase the intensity of your light sources.
In either case, please read through the following chapters in the Lightmapping Troubleshooting Guide:
I did a little experiment and found out that this was most likely due to too many objects in the scene. I will try to reduce their number or lower the lightmap settings.
Resolved, I increased the brightness of the lights
Update: Everything turned out to be much simpler, the light sources were inside the mesh. With shadows turned on, the mesh was preventing the light from propagating. I pulled the lights out of the mesh and it worked.