If you upload a prototype in run mode, it will sometimes set the initial state as your current run mode. This should not happen. Instead, when uploading, it should always zero out your interactions.
same apply for Preview in Browser. This is due to the way we build the initial HTML/CSS: for performance reasons we use the HTML/CSS from the WebView, that the first screen can be rendered faster. It is long on our backlog to first try out if we really need the special-handling for the first screen at all, or if not make it more robust that errors like yours don’t occur.