My understanding is that there are some issues with the steam cmd thingy and how it's reading the input of passwords and whatnot. There is a mention in faq's about this, but I'm not sure if the password is part of that. Make sure you read through the faq's and SS is always very good about making update posts when game wide issues have been addressed.
Make sure that you have gone to the server update option and run "save/validate." There is information about this issue in the faq's at the top of the page.
So, I say this with a word of caution. Idk if it's the "right" thing to do, but it is something I have done with both SS and other hosting sites previously and had luck because after about an hour I am an impatient caterpillar. Try closing your window, relogging into your control panel, I always use an incognito window, and seeing if you can access it then. Sometimes things hang or whatnot and what you can "see" isn't always what's really going on.
They have been very open about the fact that there has been a huge backlog of tickets this weekend. Please make sure you are checking the faq's.
I have experienced this previously on both SS and other hosting options. I know it says "don't leave the page" but I am impatient and don't listen after a while. Try closing your window and then logging back into your control panel. The server may be stopped and ready to start. Idk if you've tried that but I've had success with it in the past. GL
There is a mention of this on their faq's. You need to "update" your server. The install files didn't get copied onto your server correctly. Third dropdown on the left, "yes, run update/validate." That should fix it.