Quest State does not load because the SetState function does not execute with an error 'System.IO.EndOfStreamException' in the middle of the load.
My guess is that the number of nodes at the time of saving was 8, but the number of nodes at the time of loading is 9, so the binary Reader seems to keep trying to read after EOS.

The point at which the error occurs is line 195, QuestStateSerializer.cs.
My QuestMachine version is 1.2.17