Why can't I force close my apps in the recent apps menu?

[AC Question]

After the new update, my Lg G4 will not allow me to force close certain apps. At first, it was just my Play Store, now it is the Play Store and my email. I assume it is only going to continue adding more apps that won't force close. I've attempted to force stop them in the settings, but that does not help. You can't use the close symbol on the app when you pull it up in the recent apps option.