Quick answer: Unreal Mass spawned entities not appearing on Iris clients? Mass entities aren't network-replicated by default - use mass.iris bridge or manually replicate.
Server spawns Mass enemies; clients see empty world; only AActor-based enemies replicate.
Use mass.iris bridge
Plugin bridges Mass entities to Iris replication. Configurable per archetype.
Or shadow with AActor
For visible entities, AActor proxy replicates; Mass owns logic; AActor owns visuals.
Test with PIE + standalone
Standalone clients confirm replication. Editor-only PIE may mask the issue.
“Mass entities are not actors. Replication is opt-in.”
If you mix Mass with multiplayer, plan the replication strategy from the start. Retrofitting is painful.