I feel so bad for players using the Origin/EA App. They're able download/install the add-ons and store content, but the store content is either not staying installed or isn't showing up in-game.
This has been a long standing issue with the launcher since Sims 3 was new. They put a bandage on it to "fix" it, but now switching to a new game client again may have broke the bandage.
I did a little test install with a few of my favorite sets and a couple towns. They installed fine and are showing in-game. I installed about 50 Sims3Pack files in total. Installed them in small batches of 10 files at a time and the towns 1 at a time. (Only installed 2 of those.)
I don't think my test is quite fair though, in that I play with the original disc version (2009-2013). Patch 1.67 not attached to Origin/EA App in anyway. That I know of.
We previously downloaded Store files backed up on an external drive. I don't think ? that really makes a difference? Between using a fresh/new download of the store files vs previously downloaded files.
The Origin/EA App thing is such a mess!! There's players that are going to Steam or other means to avoid the mess. All I want to do is high-five 'em all.