Why doesn't my MultiplayerSynchronizer replicate a property change?

Each property must be added explicitly in the Replication tab. Pick the property, set sync mode (Always for fast-changing values, On Change for static state).

What's Spawn vs Sync in Replication tab?

Spawn properties replicate at scene-spawn (initial state). Sync properties replicate continuously after spawn. Most state belongs in Sync.

Visibility filter for advanced multiplayer. Default = visible to all peers. Use add_visibility_filter to gate per-peer.

Fix: Godot MultiplayerSynchronizer Property Not Replicated

Quick answer: Open MultiplayerSynchronizer’s Replication tab. Add property. Set sync mode = Always (or On Change). Save.

Player’s Health changes server-side. Synchronizer is on the player. Clients don’t see the change. Replication tab didn’t list Health.

The Fix

MultiplayerSynchronizer node:
  Replication tab:
    + Add property:  "Player:health"
      Sync:          On Change
      Spawn:         true
    + Add property:  "Player:position"
      Sync:          Always
      Spawn:         true

  Replication Config:  res://player_replication.tres   # save out

Always sends every tick (fast-changing). On Change sends only when value differs. Position = Always; Health = On Change for bandwidth efficiency.

Verifying

Server sets Health = 50. All clients see 50 within one tick. Without addition: stays at default.

“Add property. Pick mode. Replicate.”

Related Issues

For RPC silent, see RPC silent. For client prediction, see prediction.

List the prop. Pick mode. State sync.