Take a look at my Slice below

import { createSlice, createAsyncThunk } from "@reduxjs/toolkit";
import axios from "axios";

const KEY = process.env.REACT_APP_API_KEY
const BASE_URL = process.env.REACT_APP_BASE_URL
const API = `${BASE_URL}/countrymap`

const initialState = {
  mapdata:[],
  status: 'idle',  
  error:null
}

export const fetchMapData = createAsyncThunk(
  'mapdata/fetchMapData', 
  async (id) => { 
    try {
      const response = await axios.get(
        API,
        {
          headers: {
            'Content-Type': 'application/json',
            'X-API-KEY': KEY,
          },
          params: {
            titleId: id,
          }
        }
      )

      return response.data.Item;
    } catch (error) {
      console.error('API call error:', error.message);
    }
  }
)

const mapSlice = createSlice({
  name: 'mapdata',
  initialState,
  reducers:{
  },
  extraReducers(builder) {
    builder
      .addCase(fetchMapData.fulfilled, (state, action) => {
        state.status = 'succeeded'
        //This attempt to make it an array failed with the error
        //  that the state is not iterable
        state.mapdata = [action.payload, ...state] 
        console.log("map payload: ", state.mapdata);
      })
  }
})

// SELECTORS
// This works for an array, but the data is originally coming 
//  in as an object instead
export const allMapData = (state, id) => state.mapdata.mapdata.find(item => item.title_id === id); 

export default mapSlice.reducer

for reference, look at these two console logs from two different API calls to two different endpoints from two different slices . Except Media is coming back as an array, and map is an object

I need to either, turn the state.mapdata into an Object to I can use the selector the way it is or re-code the selector so that it doesn't use the .find() function because that's an array function. But either way, it needs to compare the titleId in the data to the id in the params

Sorry for not providing workable code. I would but there is an insane amount of dependencies here