Req.body return empty object with postman

Question

Good morning, I have a question. I am learning express making a transaction api. I have my put and post methods made with a console.log to see the values. But when I make the request with INSOMNIA, it returns an empty object. Look for possible answers to the problem. I already tried installing body-parser manually, changed the way of importing it and also changed the content-type to application/json but nothing works. Any advice is appreciated, ty in advance.

transaction.js

const express = require('express');
const res = require('express/lib/response');
const router = express.Router();
const mysqlConnection = require('../database');


router.get('/', (req, res) => {
    mysqlConnection.query('SELECT * FROM transactions', (err, rows, fields) => {
        if(!err) {
            res.json(rows)
        } else {
            console.error(err)
        }
    });
});

router.get('/:id', (req, res) => {
    const {id} = req.params
    mysqlConnection.query('SELECT * FROM transactions WHERE id = ?', [id], (err, rows, fields) =>{
        if(!err) {
            res.json(rows[0])
        } else {
            console.error(err)
        }
    })
})

// Borrar transaccion
  router.delete('/:id', (req, res) => {
    const { id } = req.params;
    
    mysqlConnection.query('DELETE FROM Transactions WHERE id = ?', [id], (err, rows, fields) => {
      if(!err) {
        res.json({status: 'Transaction Deleted'});
      } else {
        res.json({status: 'ERROR '+err});;
      }
    }); 
  });  
  
   // Editar transaccion
  router.put('/:id', (req, res) => {
    const {type, date, name, amt} = req.body;
    const {id} = req.params;
    console.log(type,date,name,amt)
    console.log(id)
    query = "UPDATE transactions SET type = '"+type+"', name= '"+name+"', date= '"+date+"',amt = '"+amt+"' WHERE id = "+id;
    console.log(query);
    mysqlConnection.query(query, null, (err, rows, fields) => {
      if(!err) {
        res.json({status: 'Transaction Saved'});
      } else {
        console.log(err);
      }
    });     
  }); 

 
exports.transactions = router

index.js

const express = require('express')
const app = express()
const routes = require("./routes/transactions")

//Settings
app.set('port', process.env.PORT || 3500)

//Middlewares
app.use(express.json());

//Routes
app.use("/", routes.transactions)

 //Crear servidor con el puerto
app.listen(app.get('port'), () => {
    console.log('Hola Mundo', app.get('port'))
})

module.exports = app;

database.js

const mysql = require('mysql');

const mysqlConnection = mysql.createConnection({
    
   host: '127.0.0.1',
   user: 'root',
   password: '',
   database: 'operations',
})

mysqlConnection.connect(function(err){
    if(err) {
        console.log(err);
        return
    } else {
        console.log('Db is connected')
    }
})

module.exports = mysqlConnection;

example of values

{
        "id": 9,
        "type": "Ingreso",
        "date": "2022-01-09T03:00:00.000Z",
        "name": "Trading",
        "amt": 25000
    },
    {
        "id": 10,
        "type": "Egreso",
        "date": "2022-01-10T03:00:00.000Z",
        "name": "Patente",
        "amt": 4500
    }