"Could not find static actor" errors on standalone editor client when connecting to PIE server

This seems to be due to how FObjectReferenceCache and UEngineReplicationBridge handle remapping object paths for PIE.

When creating the object reference handle, the object’s path should get renamed depending on whether the instance is/isn't a PIE instance (FObjectReferenceCache::CreateObjectReferenceInternal -> FObjectReferenceCache::RenamePathForPie). However, this isn't remapping the path as expected in the case where the listen server is a PIE instance and the client is a standalone editor instance.

On the standalone client, FObjectReferenceCache::RenamePathForPie will skip calling UEngineReplicationBridge::RemapPathForPIE, since it doesn't have a play in editor ID. This means that any paths received from the server won't be remapped.

On the server, if these object references are created before the client has connected, UEngineReplicationBridge::RemapPathForPIE will call UEditorEngine::NetworkRemapPath with a nullptr for the UNetConnection, which causes UEditorEngine::NetworkRemapPath to skip calling NetworkRemapPath_Local. This is normally what would handle stripping the PIE prefix from the path, so any object reference cache entries created on the server before the client connects will still have the PIE prefix.

This can result in the level path received on the client to still have the server’s PIE prefix, causing issues with actors placed in the level.

• Place some replicated actors in a level, with bNetLoadOnClient=true.
• Start a PIE server and have a client running in a separate, standalone editor process connect to it. (For example, use Play as Listen Server with 2 players, with “Run Under One Process” set to false.)
• Observe the “Could not find static actor” errors on the client, as well as the accompanying “Client cannot replicate object” errors on the server.