With the code on the 5.6 branch, material parameters that are texture objects (e.g. Texture2D or Texture3D) do not properly get updated when the parameter value changes.
I've created an small example to demonstrate this. When you change the texture, the property change is not propagated properly. I've also attached screenshots showing what happens.
However, I did find a commit that fixes this issue on the dev branch: d7e9c7a. I cherry-picked this commit onto the 5.6 branch, rebuilt qt3d, and the example works properly.