To reference a scene object within a MenuActionList, you need to refer to it's ConstantID number instead.
Attach a ConstantID script to your Hotspot/ActionList, copy the number, and paste it into your MenuActionList-based Action. Also, be sure to have the latest version, 1.29 as of writing.
Don't save your Cutscenes as prefabs! That's why MenuActionLists exist - they're a way of storing Actions in an asset file. If you want to call a MenuActionList outside of a Menu, you can use the Engine: Run ActionList Action from any scene-based Cutscene.
When using Actions in a MenuActionList, the object fields (such as the "New Camera" in the Camera: Switch Action) turn into "ID" integer fields - here you can enter in the Constant ID number.
Comments
Attach a ConstantID script to your Hotspot/ActionList, copy the number, and paste it into your MenuActionList-based Action. Also, be sure to have the latest version, 1.29 as of writing.
When using Actions in a MenuActionList, the object fields (such as the "New Camera" in the Camera: Switch Action) turn into "ID" integer fields - here you can enter in the Constant ID number.