This is a known problem. Does anyone from developers even read steam forums? The overlay doesn't always work. I reported this to EA support, they refused to help. No one at EA cares and they just blame the user.
The problem:
Steam overlay doesn't work. Which means you can't take screenshots, open overlay to use the chat and your playtime isn't tracked. Actually the last one is funny because you can buy the game, play it for 50 hours and refund because steam will show you've played 0,1 hours.
And please stop blaming your customers. I've played hundreds of games on steam, i also have inquisition, andromeda, titanfall 2, unravel from EA. Overlay works fine. This is the problems with sims 4 only and it's not an isolated issue, a lot of people are having it.
Solution:
Always close origin before launching the game. Close every origin process. Launch the game, see if overlay works. If not, quit the game or just alt+f4, close everything origin related and launch again. Repeat until overlay starts working. sometime it works from the first time sometime it takes 3-5 times. But overlay never works if you have origin open before launching the game.
When this all started:
I bought sims 4 last year, i think summer or early fall. It worked fine. All this started somewhere towards the end of february or early march.
Please fix this. I believe this is extremely simple to fix for developers. We just need to find out the reason. but if all you do is blame the customers we will never get a fix.