Gloomy trait conflicts with Fear of the Dark

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? 1.114.46.1030

What expansions, game packs, stuff packs, and kits do you have installed? Get to Work, Get Together, City Living, Cats & Dogs, Seasons, Get Famous, Island Living, Discover University, Eco Lifestyle, Snowy Escape, Cottage Living, High School Years, Growing Together, For Rent, Outdoor Retreat, Spa Day, Dine Out, Vampires, Parenthood, Jungle Adventure, StrangerVille, Realm of Magic, Journey to Batuu, Dream Home Decorator, My Wedding Stories, Werewolves, Luxury Party Stuff, Perfect Patio Stuff, Cool Kitchen Stuff, Spooky Stuff, Movie Hangout Stuff, Romantic Garden Stuff, Kids Room Stuff, Backyard Stuff, Vintage Glamour Stuff, Bowling Night Stuff, Fitness Stuff, Toddler Stuff, Laundry Day Stuff, My First Pet Stuff, Moschino Stuff, Tiny Living Stuff, Nifty Knitting Stuff, Paranormal Stuff, Home Chef Hustle Stuff, Crystal Creations Stuff, Bust the Dust Kit, Country Kitchen Kit, Throwback Fit Kit, Blooming Rooms Kit, and Desert Luxe Kit.

Steps: How can we find the bug ourselves?

1. Create a Sim with the Gloomy trait, or use an existing one with this trait.
2. Try to give the sim the Fear of the Dark with the cheat traits.equip_trait trait_Fear_Dark.
   • Result: The Sim does not get the fear.
3. Now create a Sim without the Gloomy trait, or use an existing one.
4. Give the sim the Fear of the Dark with the cheat traits.equip_trait trait_Fear_Dark.
5. Then, try to give them the Gloomy trait using traits.equip_trait trait_Gloomy.
   • Result: The Sim does not get the trait.
6. This issue is also observable when a Sim with Fear of the Dark attempts to gain the Gloomy trait through Growing Together’s self-discovery system.
7. I have not yet tested whether a Gloomy Sim can acquire the Fear of the Dark without cheats, but based on these results, it seems unlikely.
8. In addition, if a Sim with Fear of the Dark is given the Gloomy trait in CAS using cas.fulleditmode, the trait will be removed upon entering Live Mode—leaving the Sim with only two personality traits.

What do you expect to see? I expect Sims to be able to have both the Gloomy trait and the Fear of the Dark at the same time, whether through cheats or in-game progression.

Have you installed any customization with the game, e.g. Custom Content or Mods? No. I've removed them to test this out. 

Did this issue appear after a specific patch or change you made to your system? No, it appears unrelated to any recent patch or system change.