I can’t fully answer your question, as I’m not a whiz, but I hope I can help you.
I was actually doing the same thing as you to end my RPG, and I had no problems. The invisible character is a useful tool, and my still has glitches (like one of my Invisible Chatacters didn’t turn invisible), but that isn’t one of them.
First, I recommend that you try to open it again, if you haven’t done do already. Then, if that doesn’t work, try opening it on Internet Explorer, Mozilla Firefox or Google Chrome, depending on which one you haven’t used.
If that still doesn’t work, than try to wait it out or refresh the page. If that still doesn’t work…we’ll wait for the next update, where better things you can add will be available.
Sorry if this doesn’t help you.