Uninstalled 1 game, App uninstalled everything

I had multiple games installed:

• MySims (the original, not the re-release Cozy Bundle one)
• Sims Medieval (it doesn't launch but I kept out hope for an update)
• Sims 3 + all packs
• Sims 4 + almost all packs

I uninstalled MySims, I clicked into the game, clicked "manage" and "uninstall".

When it completed, all my installed games on the left disappeared.

I clicked into the Sims 4 and it had a download button. I've checked my programme files and it's all gone. I've checked my documents and it appears that my saves remain.

But what the hell!? Why has it uninstalled everything when I only asked it to uninstall the 1 game???!

*I also have a longstanding issue that when I launch the App some of my installed games were missing. From the installed list on the left and from my library, it would tell me to buy them again. Restarting the App fixed this but it's still annoying. I thought this had happened when I uninstalled MySims but I restarted it 4 times and it still said it was uninstalled... So I'm currently waiting for Sims 4 to completely reinstall itself AND 83 DLCs!