setInterval() and setTimeout() do nothing on heroku

Question

My Node.js app works as intended and runs without errors on VSCode. However, setInterval() and setTimeout() do nothing once my app runs on heroku. I knew this because I wrote console.log() everywhere and looked at the heroku log of my app. None of the console.log() statements inside a setInterval() or setTimeout() were executed.

Surprisingly, all other functions of this app worked on heroku.

Here is the segment of code.

var refreshIntervalId = setInterval(() => {
    config = require("./config.json");
    // console.log("index line 44: entered loop");
    if (config["reminder#" + fixedCount] == undefined) return clearInterval(refreshIntervalId);
    config["reminder#" + fixedCount]["time"] -= 5 * 60 * 1000;
    if (config["reminder#" + fixedCount]["time"] > 0) updateJson();
}, (5 * 60 * 1000));

setTimeout(() => {
    const color = "#" + hexCodes[~~(Math.random() * hexCodes.length)], userID = config["reminder#" + fixedCount]["user"];
    const userObject = client.users.cache.get(userID);
    let sendReminder = new Discord.MessageEmbed()
        .setTitle(`Reminder to ${userObject.username.split("#")[0]}`)
        .setColor(color)
        .setDescription(config["reminder#" + fixedCount]["content"]);
    userObject.send({embeds: [sendReminder]}).catch(err => { });
    delete config["reminder#" + fixedCount];
    updateJson();
}, config["reminder#" + fixedCount]["time"]);

Any idea why this happened?