Cast shadows on glass shards

Hello good folks!

I’m trying to make the glass fragments on the floor receive shadows from the walls instead of getting this emissive effect (emissive channel is empty), but I have no idea what the problem even is. The glass is set to Surface TranslucensyVolume, I’ve tried rendering with a lightmap set to the insane value of 2048, and, yes, the low poly version has all glass baked down to decals and planes instead, but I still want to learn how to solve this issue. Super grateful for all help, I’ve banged my head against this for longer than it’s worth now.