Setting expireAfterSeconds on index for ttl not working in documentDb 4.0

I am trying to make an exclusive lock semaphore using mongoose on a documentDb collection document. The index and document gets created alright, however the document never expire. I've tried turning createdAt into a string and set it to an ISO string, to no avail. Any ideas how to get ttl to work in documentDb 4.0? I can delete the document when I am done, however I want to automatically clear this in case the executed script dies holding the lock.

const mongoose = require('mongoose');
const {Schema} = require("mongoose");
const { v4: uuidv4 } = require('uuid');
const { exec } = require("child_process");

const whoAmI = uuidv4();

(async () => {

  await mongoose.connect(connectionString);

  const LockSchema = new Schema({
    id: String,
    owner: String,
    createdAt: { type: Date, required: true, default: Date.now },
  });

  LockSchema.index( { "createdAt": 1 }, { expireAfterSeconds: 30 } )

  const Lock = mongoose.model("migration", LockSchema, "locks");

  result = await Lock.findOneAndUpdate({id: "lock"}, { $setOnInsert: { owner: whoAmI}}, { upsert: true, new: true}).lean();
  if (result?.owner === whoAmI) {
    await exec("<something>", async (error, stdout, stderr) => {
      mongoose.disconnect();
      if (error) {
        console.log(`error: ${error.message}`);
        return;
      }
      if (stderr) {
        console.log(`stderr: ${stderr}`);
        return;
      }
      console.log("done...")
    });
  }
})();

TTL Index property currently is not available to DocDB Elastic Cluster.

Check the DocDB type you are using to be sure that isn't the problem. I was using DocDB 5.0 but it was the Elastic version, this could have saved me a lot of time.

You can check the docs with the available features here: