Hello,
This bug isn't limited to sleepwear. Often when I'm starting an athletic interaction, the game INSISTS on changing to "Athletic 2" even when the sim was already in "Athletic 1". If during the interaction I use "testingcheats true" and then go into "Modify in CAS" while the Sim is still working out, it will incorrectly show the "Athletic 1" outfit button as active, while the Sim is actually visibly wearing the second outfit.
The game just seems to become confused about which outfit the Sim is wearing if there is more than one variant. I've stopped using more than one outfit per category simply because of this bug, since it makes multiple outfits unpredicable (you can't safely choose which one you want to wear anymore).
I have actually already reported a variant of this but it seems that nobody noticed: http://answers.ea.com/t5/The-Sims-4/Bug-quot-Everyday-1-quot-outfit-enforced-when-going-to-work/m-p/3443547 (same bug, other outfit affected)
Merged your old post.
Referring to #lord_eimeron's variant.
What seems to be happening with the work outfit is: If you are wearing sleepwear when your Sim heads to work, the game changes you into your work wear, but then changes you into an "outdoor" outfit immediately after. The game seems to think you are inappropriately dressed to leave the lot - not realizing that it has already swapped your skivies out for for work clothes.
This seems to happen with swimwear sometimes too, but I haven't been able to confirm this for certain.
