$evars$ are expanded by litestep before skinbox has a chance to do anything with them. It's not possible for it to be messed up, most likely it's expanding to something including backslashes, which skinbox tries to evaluate. Either use \d or surround it with the block escape: {["$path$"]}

For example:

If all else fails, put in !alert 'original setting' and you can see what it's expanding to.