Why can't I set a variable on an actor after spawning it

I am trying to understand why I am having problems setting a variable per actor after spawning it.

I have an actor with an integer variable. The variable is instance editable and exposed on spawn.

I does work, if I am setting it directly when spawning the actor.

However, if I try to set it after SpawnActor, it doesn’t work.

Can someone explain this? Is the object not “ready” yet to be modified?