Diffuse baking - extremly weird result (cycles) I try to bake the diffuse map of my box model in cycles render engine, but I get extremly weird results:

I made a short video:
https://youtu.be/bwoLJ8psZ2E


This is my model:





it is a model which consists of multiple smaller models which I have joined at the end, thus it has multiple materials:





First I created a new UV-Map and choosed Smart UV-Layout.







Then I created a new texture in the UV-Panel





Next I hit bake:





This is the result:





...and if I select the original UV-Map then it looks like this now:





I am not sure why this does not bake as expected.


If I do the same method with another model which has only one material, then it works without problems.
I solved it, I had to add the texture bakeResult0001 created at step #4 to each material as none connected image texture node, I also had to only check "color" in the bake settings, otherwise weird black spots were baked onto the texture.



I created a video: https://youtu.be/nOvtGUgWCA0