I have been thinking about Blackboards serializer, but I never got a response from the creator of Unreal’s Behavior Tree system on GitHub, ever; there’s some API access required that is simply private code, I haven’t tried it again since a long time tho.
You would have to manually feed your BT with values saved on character BP.
The plugin does not record the state of trigger volumes.
You have to create a boolean property, mark it “Save Game” and implement the Serializable interface.
From On Loaded interface event, check again the value of the boolean and disable trigger collision detection based on value of that boolean.
(see saved ragdoll effect in demo project, same process)