itch.io

Essentially you need to remove the "Task Completed" variables / functions in the state tree blueprints (Prefix ST...) and just replace it with a "Finish Task" node (or something similar), as this works properly now. 

Unfortunately its not properly supported, you can still import it into UE 5.3 but need to make some changes to the code. Specifically the workaround for a bug that was present in UE 5.1. Its mostly in blueprints so if you know how to use that then its fine.

Its related to the "Task Completed" variables when you load it in. You'll notice the errors when you try doing anything so that should guide you too hopefully.
Most of the rest of the code should work though.