Sims 4 Get To Work - Won't Install.

Hi, I purchased the Sims 4 'Get To Work' expansion pack, but when I try to install it, it won't. 

Autorun comes up with the same message (click here to view) saying that I need to Update the Sims 4 base game before it will let me install the expansion pack. However, the base game is fully up to date every time I check and doesn't need any updates nor gives the option to do so when logged into Origin. I only updated the base game a couple of days back. How do I solve this problem and successfully install the 'Get to Work' expansion pack? Is there a way around this?

Thanks in advance.