Walls suddenly below character?

I recently built a map and had it set up how I wanted it. I tested it out and made sure to check in my database that all objects I wanted to be impassable were marked with an x. Now, after I've added a few events, my character can suddenly walk on the walls (as well as my randomly moving NPC's). I'm not sure what to do. I've checked the database for my game and I have these tiles marked with x's so they shouldn't be able to be walked upon.

Any advice? Can an event somehow trigger this problem?

Is the first tile in Tile B set to a star?

Nope! Not sure how it got changed, since I see it's usually defaulted to that. Thank you.