Next state keep resetting

I'm unsure what triggers this so I'm going to describe my setup, but I'm certain there's something going here.

I have a state machine created like this

Everything besides DinerStateRoot has a script extending the State script and annotated with @tool.

The next_state var keeps resetting to something I did not choose. For example:

IdleState is suppose to have SelectionState set as its next state, but someone always triggers the editor to set it to IdleState (itself).

Any idea why?