IBakedModel just doesn't work for blocks. What i tried:

 

1) Set IStateMapper for block to point on model resource location

    Register IBakedModel in ModelBakeEvent with location above

 

2) Iterate all block model locations which is used by default in DefaultStateMapper

    and register IBakedModel for each location

 

Interesting facts that i found:

 

1) Minecraft.getMinecraft().getBlockRenderDispatcher().getModelForState(block)

  always returns right model that i set in event

 

2) Even if call above return right model, model is missing in hand and in world

 

3) Steps above work perfectly for items (excluding IStateMapper)

 

Don't ask for full code. I'm pretty sure that details above is enough.

However, if it REALLY will help finding solution (it won't because it's internal minecraft problem),

i can demonstrate example code.

And please don't say to use TESR. I won't use it anyways.

 

 

The issue you are having is not a problem within MC's internals. The question is: What are you trying to achieve with the custom IBakedModel? I am already using custom IBakedModels in multiple mods, for example to create a block with connected textures. To be able to help you, we need at least your IBakedModel implementation.