Do you remember what event you played before the problem started?
Going to the bathhouse or any other location, where your party splits, will fix the issue.
I made a new option in the cheat book in your bedroom, which will allow you to reset the related switches and fix the issue. But since you can't add files to the browser version, to update the map file yourself, you'll have to wait to the next update before the option becomes available
Sorry for the trouble.