Ideas
I have the same issue too. Preparing for the new patch updates, I removed all my mods and CC from the Sims 4 folder, deleting all caches, disable script mods and custom contents. Restarting the game and started a clean new save file. My sim caught a fire on his first cooking, and the firefighter who came to the rescue wore that headbow, instead of their hat. I also noticed that CAS stuff that we get from event rewards have higher tendency to be use by newly generated townies, as same thing happens to the neck scarf we get from cozy event, but maybe it is not too noticeable as sims usually wear it on other outfit categories, not everyday, I forgot which one. And also regarding the headbow, using the styled looks would not automatically remove it, somehow it stays on the sims, so I need to remove it manually by going to the headband section. Maybe this is related to why any service sims (firefighter, maid) who have that headbow won’t wear their respective job’s hat.
I play on PC (Win10), through EA app. My game version is 1.117.244. I only have base game Sims 4, I do not have any packs.