AttachChildren on the client can lose entries

If a client attaches a scene component to a server authoritative scene component and that server component later has a change in attachment made on the server, the AttachChildren array on the client will no longer contain the component attached on the client.

In QAGame using QAPawn blueprint add 3 key events

Key O should spawn an emitter attached to the pawn's mesh
Key P calls a replicated event which, on the server, adds a decal component to the pawn and attach it to the mesh
Key H should print out the result of GetNumChildrenComponents on the pawn's mesh

Change Mesh components replicates property to true.

Run PIE with 1 player and a dedicated server.

Press O and then H and see that the count is 1
Press P and then H and you would expect to see that the count is 2, but it will output 1