Directional Light (Mixed Baking) - Shadow issue at certain angles

This may be an issue with the update to 5.4 (I have updated the lightmaps due to the changes to the engine and Enlighten).

Above you'll see the pitch that has been lightmapped (some of the large stadium shadow can be seen in the bottom left). However when the camera is at certain angles - the whole pitch gets darker. This can be prevented by turning off shadows on the directional light (or turning off the directional light altogether). The reason the dir light here is set to affect the pitch at all, is so that it can receive shadows from the players. This has worked well in the past. It's an odd issue.

The problem isn't specifc to this custom shader (I've found the same by using just the standard shader).

 

It's a bug in the lightmapping system that is desperately being fixed right now. That mixed mode is just insanely broken...