Edge Detection with Vision HDL Sobel Block in Simulink not working

I am trying to do what is told in the according tutorial, just without the overlay. The Sobel block is packed between frame-to-pixel blocks with according dimensions (working without the Sobel block). Non-HDL implementations work fine in Matlab and Simulink. Sample time in the image block is 0.2, but didn't work with other values as well.

Still I don't receive the result, it just gives me a black image (with the right dimensions). What am I doing wrong?

Edit: Median Filters are bringing the same result. Line buffer has been tried with 512, 2048 and 4096 without change.

[Bharath Venkataraman]

Peter, do things work when you connect the Frame To Pixels output to the Pixels to Frame block?

Please upload the model and image and I can try to take a look to see what the issue is.