Comment by jansan

As I wrote in the post above, masks and filters are not not supported, yet.

For your icon a clip path may make more sense than a mask. If you want to create an icon with the same shape you can simply take the elements from the mask and paste them into Hyvector and work with that:

<circle cx="10" cy="10" r="10" fill="white"></circle> <path d="M15.41 16.59L10.83 12l4.58-4.59L14 6l-6 6l6 6l1.41-1.41z"></path>