Unity won't allow me to assign a child object to a variable of type parent object

I am creating a Finite State Machine for use in Unity for an enemy in a game.

All the states are made from an EmptyState.cs blueprint that defines the state exit, update, and start functions, and all states are derived from it.

In my FSM core, I have a dictionary reference to all states, and the current state;

private Dictionary<Type, EmptyState> amalgamStates;

public EmptyState currentState;

The dictionary, looks like this;

Dictionary<Type, EmptyState> states = new Dictionary<Type, EmptyState>
{
    {typeof(RoamingState), new RoamingState() },
    {typeof(IdleState), new IdleState() },
    {typeof(StalkingState), new StalkingState() },
    {typeof(HuntingState), new HuntingState() },
    {typeof(HauntingState), new HauntingState() },
    {typeof(LeavingState), new LeavingState() }
};

However, when I assign a state to currentState, it always sets as null.

 private void Update()
 {
     if (currentState == null)
     {
         currentState = amalgamStates.Values.First(); **<--- here**
         Debug.Log(currentState); 
         currentState.stateStart(amalgamBrain);
     }
     //Run state's update and store output (output will be next state)
     var temp = currentState.stateUpdate(amalgamBrain);

     //If the stored state is different -> switch states to new state
     if (temp != currentState.GetType())
     {
         switchStates(temp);
     }
 }

Debug.Log(currentState); always returns null. I can't even set the variable manually in the unity inspector.

I know that this should work, as I am working from a project of a similar framework that works fine, so I'm just making a dumb mistake somewhere. Does anyone have any ideas? Here is the entirety of EmptyState.cs to anyone curious.

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class EmptyState : MonoBehaviour
{
    public AmalgamCentralAI amalgamBrain;

    public virtual void stateStart(AmalgamCentralAI amalgamBrain) { }
    public virtual Type stateUpdate(AmalgamCentralAI amalgamBrain) { return null; }
    public virtual void stateExit(AmalgamCentralAI amalgamBrain) { }
}

EDIT: Just some additional context;

the states dictionary is part of another script that is populating the one titled amalgamStates.

I will post the relevant scripts here in its entirety.

AmalgamCentralAI.cs

using System.Collections;
using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AI;

public class AmalgamCentralAI : MonoBehaviour
{
    private float stunHealth;

    public bool playerInSight;

    public Transform interuptedEvent;

    public GameObject playerTracker;

    public Transform[] leavingAreas;

    private int tensionMeter;

    public AmalgamFSM FSMLogic;

    private void Start()
    {
        interuptedEvent = null;
        FSMLogic = GetComponent<AmalgamFSM>();
        Dictionary<Type, EmptyState> states = new Dictionary<Type, EmptyState>
        {
            {typeof(RoamingState), new RoamingState() },
            {typeof(IdleState), new IdleState() },
            {typeof(StalkingState), new StalkingState() },
            {typeof(HuntingState), new HuntingState() },
            {typeof(HauntingState), new HauntingState() },
            {typeof(LeavingState), new LeavingState() }
        };
        Debug.Log(states);
        FSMLogic.GrabAllStates(states);
    }

    private void Update()
    {
        trackPlayerVisability();
    }

    private void trackPlayerVisability()
    {
        RaycastHit hit;
        if (Physics.Raycast(transform.position, playerTracker.transform.position, out hit, Mathf.Infinity))
        {
            if(hit.transform.tag == "Player")
            {
                playerInSight = true;
            }
            else
            {
                playerInSight = false;
            }
        }
    }
    
}

AmalgamFSM.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

public class AmalgamFSM : MonoBehaviour
{
    public AmalgamCentralAI amalgamBrain;
    public Dictionary<Type, EmptyState> amalgamStates;

    public EmptyState currentState;

    private void Start()
    {
        //Fetch all Amalgam Commands
        amalgamBrain = GetComponent<AmalgamCentralAI>();
        //Start in Roaming State
        
        //Debug.Log("state start");
    }

    private void Update()
    {
        if (currentState == null)
        {
            currentState = amalgamStates.Values.First();
            Debug.Log(currentState);
            currentState.stateStart(amalgamBrain);
        }
        //Run state's update and store output (output will be next state)
        var temp = currentState.stateUpdate(amalgamBrain);

        //If the stored state is different -> switch states to new state
        if (temp != currentState.GetType())
        {
            switchStates(temp);
        }
    }

    public void GrabAllStates(Dictionary<Type, EmptyState> states)
    {
        //Fetch dictionary of all states
        amalgamStates = states;
    }

    public void switchStates(Type state)
    {
        //Run current state's exit, create reference to new state, run new state's start
        currentState.stateExit(amalgamBrain);
        currentState = amalgamStates[state];
        currentState.stateStart(amalgamBrain);
    }
}

RoamingState.cs

using System.Collections;
using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AI;

public class RoamingState : EmptyState
{
    private float SearchRange;
    private Transform centerPoint;
    private bool pointFound;

    private NavMeshAgent agent;

    public override void stateStart(AmalgamCentralAI amalgamBrain)
    {
        //Define search range
        SearchRange = 100f;
        //Amalgam serves as the center of the search area
        //Debug.Log("fetching center point");
        centerPoint = amalgamBrain.gameObject.transform;
        agent = amalgamBrain.gameObject.GetComponent<NavMeshAgent>();
        pointFound = false;
    }

    public override Type stateUpdate(AmalgamCentralAI amalgamBrain)
    {
        if(!pointFound)
        {
            //Find suitable Roam Position
            Vector3 point;
            if(RandomPointOnNav(centerPoint.position, SearchRange, out point))
            {
                //Set roam position in navmeshagent
                agent.SetDestination(point);
                pointFound = true;
            }
        }
        // if the agent is close enough to the random point
        else if(agent.remainingDistance <= agent.stoppingDistance && pointFound)
        {
            //idle
            return typeof(IdleState);
        }
        //if agent is still looking for a point or is travelling to a point, remain in roaming state
        return typeof(RoamingState);
    }

    public override void stateExit(AmalgamCentralAI amalgamBrain)
    {

    }

    public bool RandomPointOnNav(Vector3 centerPoint, float range, out Vector3 resultPoint)
    {
        //Find a random point in a sphere of searchrange radius around the amalgam
        Vector3 RandomSearchPoint = centerPoint + UnityEngine.Random.insideUnitSphere * range;
        NavMeshHit hit;
        // Can the amalgam travel to this point on the navmesh?
        if (NavMesh.SamplePosition(RandomSearchPoint, out hit, 1.0f, NavMesh.AllAreas))
        {
            //return that the amalgam has found a suitable position
            resultPoint = hit.position;
            return true;
        }
        // if not remain still and continue searching on next update
        resultPoint = Vector3.zero;
        return false;

    }
}

Just an additional point I found weird.

    currentState = amalgamStates.Values.First(); **<--- here**
    Debug.Log(currentState); 
    currentState.stateStart(amalgamBrain);

in the currentState.stateStart(amalgamBrain);, even though debug.log is returning null, it does run the stateStart of the First amalgamState, which is the RoamingState.