Soft synchronization bug during additive scene loading

[austinplane]

Description

I am using an additive scene architecture, with a PersistentScene containing a singleton NetworkBehaviour for scene control (SceneController).
When a client joins, the PersistentScene is synced, loading the SceneController into the ScenePlacedObjects Dictionary.
When the additive scene is synced (OnClientBeginSync), the ScenePlacedObjects Dictionary is cleared.
When SynchronizeSceneNetworkObjects runs, the InternalBuffer still has a reference to the SceneController, and the globalObjectIdHash is passed to GetSceneRelativeInSceneNetworkObject.
The ScenePlacedObjects does not contain the key for the SceneController, and returns null, leading to the Soft Synchronization failure.

Actual Outcome

See attachment.

Expected Outcome

Additive scene loads without trying to load SceneController NetworkObject

Screenshots

See attachment

Environment

• OS: Windows 10
• Unity Version: 2022.2.5
• Netcode Version: 1.3.1
• Using Facepunch for transport

Additional Context

I can send project privately on request
Soft sync bug.pptx

[austinplane]

This appears to be fixed in develop branch, maybe due to #2383 ?