Hint 1
You have the right idea. Take note of the geometry of the left side of the puzzle when looking for safe tiles to leave snow on, there's one that is easy to miss.
Hint 2
Revisiting Sort from the Snow area might help.
** The details and summary tags are not working for me..
For those that are still struggling with this like I was: The first hint led me down the wrong path because it made it seem like the left snowball is the problem and not the right one in OP's screenshot but it's the other way around actually.
