This happens to me randomly all across my project. Sometimes after baking lights that are marked as Mixed, they produced an incorrect result. The Realtime part of it disappears and the lightmap produced is as if they were marked as Baked.
Here is an example where I have two spot with the exact same settings, the one one the left bakes correctly showing the indirect produced by it, while the one in the right is baking also the direct component.
Also, even though in the normal inspector I can see that both are set to Mixed, on Debug mode it seems they have been baked with different settings. Why is this?