I am having that exact problem as well. I have a SQSP domain, ismycueready.com, which I need to point to a specific page on my site (52cues.com/feedback).
I even have a 301 URL redirect set up that should point to the new page (/feedback). But it just...doesn't. It keeps going to 52cues.com.
So...I'm interested to see if you get any responses to this!
Shannon