No Respawn of special NPCs

Game mode: [Online | PVE]
Problem: [Bug ]
Region: [Jungle]

[In the south east corner of the map is a little island with a camp of a few dancers (in german: Insel der hässlichen Sirenen) I build a bridge to catch a few of them. But now my bridge is finish and they dont respawn. Even after a server reset camp is empty]

Steps on how to reproduce issue:
1.Kill Sirenen
2.Built a bridge
3. Wait on respawn