OK, there might be something here.
I run some tests and the weird steps for proper baking with normal maps are:
- Make a new project with normalmap set to DIRECTX
- stamp some normalmap decals
- export both DIRECTX and OPENGL normal map as a 16bit .tif
- import it to project and put OPENGL normalmap into normalmap slot in TextureSet Settings
- bake ao
- replace OPENGL normalmap with DIRECTX one for further work and export.
Then i made different case with OPENGL project, where you have to use DIRECTX normalmap for proper results.
It seems like your baker bakes properly only with normalmap that is NOT compatible with projects settings.
