use expansion packs on ea through steam?

livbanjo​  Do you have another computer to test with?  You wouldn't need to be able to play on it, just borrow it long enough to install the game.  I'm wondering if this is some kind of account issue that doesn't look like normal account issues (the ones where people can't access their content at all).  If you have the same problem on the other computer, it's likely, although not certainly, an account issue; if you don't see the same problem, the cause is on your main computer.

If you don't have access to another computer you can test with, try the same suggestions, except this time, create a new admin Windows account and reinstall the game using that account.  Additionally, if you use a third-party antivirus, disable it before reinstalling the EA App, and leave it disabled while installing Sims 4 and your packs.

You can test with just the base game through Steam to save time; no need to install all your content for testing purposes.