that's how it works, quote from mod page:

Q: How do notification icons work?
A: Notification icons show up only if they are turned on in sandbox settings. Green icon: friendlies, red icon: raiders, yellow icon: wanderers and the violet icon are the bandits' bases, The icon points to the spawn location, not the actual position of any bandit. The icon will not vanish automatically. To make it go away, double click it.

Thanks!