As you can see on your demo app, when you zoom on Mona Lisa, on the right side :
You can see every tiles being stretched.
It is not very highlighted in this example.

The problem is more visible on this image :

I have try to put my tiles in your demo and it worked perfectly in precedent library, but since the new one, the right side images are stretched.

This is the right image to display :

thank you for your help