5.2 Patch Notes

Had some reports come in of several multiplayer bugs in engine in 5.2, tracked it down to a specific commit from Epic.

Many might want to be careful updating to 5.2 if you are doing a multiplayer experience. The bug effects local attachment of things (hands for example) to replicated scene components (actors). Currently when the actors attachment replication comes down its overriding local states for a components attachment, there is no way for me to fix this plugin sided as its nested too deeply in engine and requires an engine modification to fix.

Visually this will present with the component locally being attached flipping back to its old parent but at the new relative transform if you change parents within ping time on a client

Offending commit (can reverse changes in SceneComponent.cpp to fix the problem).

https://github.com/EpicGames/UnrealEngine/commit/7931f4822cbe31812689de072d0a8e44e3847b06

Specifically what they changed in SceneComponent.cpp where its forcing child components to change their parent (even though scene components replicate their parent themselves as well). It doesn’t even call OnAttachmentChanged on the child either so it doesn’t follow proper procedure regardless.