Maz, It shouldn't make any difference that you have several domains. What I'm wondering about is whether your installation of SD went haywire somehow.
Could you try to uninstall it, and then redownload and reinstall it? After that, open SD and make something, a test project, with say, some bit of text, one background image and one foreground image, and if you haven't used up all 10 domains, upload it to an available one and see how that goes? And let me see the folder structure of that.
I see you are a Mac user, so you could download the FTP client FileZilla and try a transfer using it.