Missing basegame clothes in CAS

Product: The Sims 4
Platform:PC
Which language are you playing the game in? Français
How often does the bug occur? Every time (100%)
What is your current game version number? 1.108.349.1020
What expansions, game packs, and stuff packs do you have installed? Holiday Celebration Free Pack, Get to Work Expansion Pack, Luxury Party Stuff Pack, Spa Day Game Pack, Spooky Stuff Pack, Get Together Expansion Pack, Romantic Garden Stuff Pack, Backyard Stuff Pack, Vampires Game Pack, Toddler Stuff Pack, Jungle Adventure Game Pack, My First Pet Stuff Pack, Get Famous Expansion Pack, Moschino Stuff Pack, Realm of Magic Game Pack, Discover University Expansion Pack, Tiny Living Stuff Pack, Eco Lifestyle Expansion Pack, Nifty Knitting Stuff Pack, Snowy Escape Expansion Pack, Paranormal Stuff Pack, Fashion Street Kit, Blooming Rooms Kit, Werewolves Game Pack, Book Nook Kit, Castle Estate Kit
Steps: How can we find the bug ourselves? Searching a specific basegame short dresses in CAS, or adding a household in which a Sim is supposed to wear the dress.
What happens when the bug occurs? This specific short dress from basegame doesn't appear in CAS. Premade Sims wearing said dress appear with no dress when added to a save.
What do you expect to see? The return of the dress or any item that have been gone in a similar fashion.
Have you installed any customization with the game, e.g. Custom Content or Mods? Not now. I've removed them.
Did this issue appear after a specific patch or change you made to your system? No

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Hello,

This is a problem I noticed earlier but didn't pay any mind to it until I noticed a character from this household was affected by this issue: in this household, Samantha Gratz uses a dress in her formal outfit that is gone from my game. When I first tried to edit the household in CAS, I got a notification that some item was gone, like I would have if the household had items froms DLCs I don't own. But this household only uses Vampires and basegame stuff. This household also shows up on the gallery and in my library with the green icon telling I do not own all the DLCs necessary for it (despite me owning the Vampires GP).
Upon further investigation I noticed it's the same basegame dress I've been unable to find in CAS since a few days.

I tried geting rid of my mods, cleaning my cache, repairing my game, and updating to the latest version. The dress is still gone.

I did find it in Sims 4 Studio however, so I guess it's still somewhere within the game.

Edit: Now that I think about it, I've seen this not-owning-packs notification on gallery/library elements for a while, concerning DLCs I do own. So far I can say this also occurs for:

• The household called "Malpractice" (I can't say for sure what's missing, but Kai kahue and Chris Foley don't wear clothes aside from shoes and glasses for their formal outfit).
• The household called "Still Life" (no idea what's wrong with this one)
• The household called "Wolfie & Clawde" (Bianca Barov seem to have lost her dress in the formal outfil too)