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That seems to have fixed things! Thanks so much for the reply; I really appreciate the support you all offer for Bolt.

I'm not really sure how to upload a project for testing. I could probably get you access to my repo if the info above isn't sufficient to give any clues. Oh, also, I'm now on Unity 2018.3.0f2, and Bolt 1.4.0f11. Thanks for your time reading this!

Ok, after a while of not seeing this issue I'm seeing it pretty regularly now. It shows up in a few different forms:

I have a dedicated scene for my UI, with an embedded state machine on my main UI gameobject. When I run just the UI scene by itself, the state machine behaves as expected. When I load the UI scene in additively at runtime, the state machine switches its source to Macro and the embedded graph is lost. Strangely, when I exit play mode, the source stays set to macro until I exit and relaunch Unity, at which point the embedded graph is restored.

I also have a player prefab in my Resources folder that I'm instantiating at runtime. It has a state machine attached with a macro as its source, but when it's instantiated it loses its reference to the macro as well as all its object variables. Similarly, after I exit play mode and inspect the prefab, the state machine stays set to Macro with an empty reference to a macro file until I restart Unity.

I get the following error when running my project: