Game mode: [ Single-player ]
Type of issue: [ Bug ]
Region: [ Europe ]
Mods?: [ No ]
Custom Server Setting?: [ No ]
Similiar to: No bosses spawning in vaults (But only mentioned Bosses)
Any Vault is missing NPCs like Mobs, Bosses and whatever there might be in.
Mobs eventually? The Vaults are completely empty for me.
Go on Singleplayer and check for yourself.