Loss does not decrease during training a CNN

Hi, I am running an example of Matlab Deep Learning Toolbox as follow: https://se.mathworks.com/help/images/single-image-super-resolution-using-deep-learning.html

However, the loss does not decrease as conventional neural network does (I have just run the code without any changes). It is luctuating between a value. Is there anything wrong here?

Thank you very much.

[Gizem Yüce]

I am having the same issues in matlab r2016a, which matlab version are you using and could you solve the problem?