Mixed Spotlights not included in baked lightmaps, only Baked spotlights

I figure this is probably an issue with my settings, hopefully, but so far I haven't found a setting that resolves this. Basically, when my spotlights are Baked, things bake properly. When they're Mixed, only a portion of the lights get backed into the lightmaps. I'm using HDRP, and trying to bake lighting in a trivial scene with just a floor and 8 spotlights in it, each a different color to tell them apart. Here's what it looks like:



The above was baked with all Baked lights. However, if I simply change the lights to Mixed, the lightmap bakes completely black. Why would Mixed lights bake differently than Baked lights?


I tried some more experiments, changing the light settings. Just to show it, here are my lighting settings for this scene:



Does anyone know why Mixed lights wouldn't bake into the lightmap? I've tried Progressive CPU, Progressive GPU, and Enlighten. I've tried Baked Indirect and Shadowmask. It doesn't change the outcome.

 

Okay, it seems I missed the point of Mixed entirely. Only indirect light is baked into the lightmaps, not direct light, so my example here with just a single plane means there is no indirect lighting.