All right, I have found the solution for the problem.
Dont know why but using Gst.Bin as sink to the streammux does not work.
Finally I have append the uridecodebin inside Gst.Bin, converters and caps filter for every stream are outside of GstBin.
You can take a look at the pipeline and see the differencess between the first pipeline I have added.
The above pipeline is also solution for the problem what I mentioned in the topic:
multistream cropping problem
So the question is why the GstBin is not working as expected?
What did I do wrong?