Stuck in build/buy mode when going to live mode

@Xemternort  Please undo the compatibility setting: Sims 3 runs just fine in Windows 10, at least most of the time.  Please also move your entire Sims 3 folder out of Documents\Electronic Arts and onto your desktop.  When you launch the game, a clean folder will spawn with no content.  Don't add anything to it yet; the point is to test with a completely new set of files.

Restart your computer, load the game (but no other programs), and start a new save in Sunset Valley.  (You'll see the tutorial again, but you can exit out of that quickly by clicking the three dots in the lower left corner of your screen and selecting Edit Town, then going back to the game setup.)  Pick a premade family, let the game clock run for a sim-hour or so, play around in Build/Buy for a few minutes, and try to go back to live mode.  Let me know whether it works.

If you can't get back to live mode, please run a dxdiag and attach it to a post.

https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/

Please also list the packs you have installed, and what type of install this is: Origin, disc, Steam, or something else.