I gave my club a cool club outfit but none of my Sims are wearing it
The cause for this issue is the same LastException that causes the endless generating of Father Winter. The LastException also prevents Sims from changing into their club outfit. Luckily that’s all that happens. There’s no endless trying to do so that could cause further issues.
On top of this there’s also an older LastException that causes the Sims to not change clothing at all anymore as long as you’re in a club meeting. If you defined one, it will be removed. The same exception also gets triggered on retail lots that use mannequins. That doesn’t seem to have any visual effects other than the LE though.
I would currently not define any club outfits.