It seems like it only happens in Chrome and Safari.. not Firefox. I\'m using it with the foundation responsive framework so I\'m not sure what to do about setting the height.
In case you have the dimensions of the images available you could do a workaround with SVG placeholders.
For example: Use a figure element and position the img with "position: absolute" on top of the svg.
This way isotope renders the gridelement with the SVG that occupies the space and puts the img on top it.