Hi.
As some of you may already know, Unity has finally release a massive improvement on the prefab workflow, allowing us to have prefabs within prefabs. This is available on the beta "2018.2b improved prefab".
I tried it these last few days and found an issue with Playmaker. With the new system we have a prefab mode, it's like having a new scene for prefab edition. Though playmaker will still allow editing of the FSMs from the project folder, before entering prefab mode: these modification won't work and the editor should be locked outside of prefab mode.
Thanks.