That dress broke with one of the patches, months ago. My installed version was broken after a patch, and I know I did not re-download it in the meantime.
I have since re-downloaded a few times, but it's still broken, as you say.
Elsewhere on the forum somebody reported that an EA tech told them to use a program called S3RC to fix it. This is an external program. It's main use is to strip down pirated content so that it installs properly. As a 'side effect' the dress is fixed.
It does work, but I don't think it's right to tell people to get an external program to fix store errors. Let alone a program that is designed to strip 'store identifiers' from content so that it can be shared.
Either EA doesn't know how to fix it so that it works but still has 'anti-piracy' identifiers. Or they just can't be bothered to fix it - or even to take it off the store to prevent people from buying a faulty item.
BTW, the 'elder' version of the dress still works.