I voted!
It says 5.4 targeted fix, that is terrible news, I guess they don’t care about those that use baked lighting now Lumen has come along 
It does also say to mention the issue logement in the thread too, so here it is: UE-195177
The bug report says “Emissive material lighting falloff regression in GPU Lightmass”
I don’t get ANY lighting from emissive material when baked, doesn’t matter how intense I make the material (this is in 5.3.0)