Can't add to the wishlist & can't purchase

For about a month now, when I log into the EA app, I have not been able to add The Sims 4 add-ons that I haven’t purchased yet to my Wishlist.

Another issue is that when I try to purchase any add-on for the game, I receive an error message. This happens both within the EA app window and inside the game itself. 

(A Mac User)