[FIXED] Placing stairs next to half wall freezes the game

Product: The Sims 4
Platform:PC
Which language are you playing the game in? English
How often does the bug occur? Every time (100%)
What is your current game version number? n/a
What expansions, game packs, and stuff packs do you have installed? Cats and Dogs, City Living, Get Together, Get to Work, Jungle Adventure, Parenthood, Vampires, Dine Out, Outdoor Retreat, Laundry Day Stuff, Vintage Glamour Stuff, Romantic Garden Stuff, Movie Hangout Stuff, Spooky Stuff, Cool Kitchen Stuff, Perfect Patio Stuff, Holiday Celebration Pack.
Steps: How can we find the bug ourselves? Create a deck that is 4 squares wide. It doesn't matter how long the deck is. Set the foundation level to maximum height. Set wall height to medium. Looking from the side that is 4 squares wide, place a wall on the right-most edge of the deck that starts at least one square into the deck and extends past the deck at least 2 squares. On the left-most edge, place a wall with the same length and position as the other, but make the wall a half wall, and make it the second shortest half wall height. Place a staircase touching the right "full" wall and going into the deck. Click the staircase and, when the arrows appear, drag the staircase to the left to extend it all the way until it reaches the half wall. Let go of the arrow to finish the extension.
What happens when the bug occurs? The game freezes, can't do anything on computer, have to press Ctrl-Alt-Delete to escape and close game.
What do you expect to see? the staircase extends as normal and no game freezes occur.
Have you installed any customization with the game, e.g. Custom Content or Mods? Yes
Did this issue appear after a specific patch or change you made to your system? Neutral/Not Sure 

‌

A Video demonstrating the glitch. The glitch also

occurs when I place the staircase directly next to the

half wall, and even when I place the staircase

elsewhere and move it to the wall.