The old Scirra Arcade is quite old, and a bit broken now, and we will be replacing it in the future.
So, for now, we'd recommend uploading to another online portal such as Newgrounds, Kongregate or itch.io. The links here are to resources about uploading a game to each site.
If you can't see your game file where you think you it should be, it might be worth downloading it again anyway, just in case something's gone wrong!