Hello LavynderSylk. It sounds like you've found a "hidden" trap door in the north bathroom. If you drop your little person closer to the middle of the sink (or to the right of the sink), they will not end up in the small central room.
When your little person appears to be stuck on the shower, does their "action line" seem to cycle through different actions/tasks without actually going anywhere? If so, and you have any decor items near where you're dropping them, they may be getting caught between the item and the shower. Try moving the item and place your little person at the shower again.
Many families seem to prefer one bathroom over the other. This is normal. I've also had peeps who would not go into the toilet area when I dropped them there. They would only go on their own when their action said "Nature is calling." They certainly have minds of their own!
I hope this helps!