Creating an index causes unauthorized error

I'm working on a project using Go microservices connecting to an Azure CosmosDB.
On the dev / stage environment I'm using the MongoDB API 3.6, for production 4.0.

The microservices creating indices on the collections. For the dev / stage environment all work's fine. But on production I'm retrieving the following error:

> (Unauthorized) Error=13, Details='Response status code does not
> indicate success, Number of regions attempted:1

I've checked the connection string twice and currently there are no firewall rules for the production db.

My code looks familiar to this:

package repository

import (
    "go.mongodb.org/mongo-driver/mongo"
    "log"
)

func Collection(db *mongo.Database, c string, indices ...mongo.IndexModel) *mongo.Collection {
    col := db.Collection(c)

    if indices != nil {
        _, err := col.Indexes().CreateMany(ctx, indices)
        if err != nil {
            log.Fatal(err)
        }
    }

    return col
}

// .....

package service

import (
    "go.mongodb.org/mongo-driver/bson"
    "go.mongodb.org/mongo-driver/mongo"
    "go.mongodb.org/mongo-driver/mongo/options"
    "repository"
)

col := repository.Collection(db, "my_col", []mongo.IndexModel{
    {
        Keys:    bson.M{"uuid": 1},
		Options: options.Index().SetUnique(true),
    },
}...)

Anyone an idea what causes this error?

I've contacted the Microsoft support and this is what they replied:

> This is a limitation of accounts with Point in Time Restore. The collection must be created with a unique index.
>
> https://learn.microsoft.com/en-us/azure/cosmos-db/continuous-backup-restore-introduction
>
> You can use a command such as this to create the collection with the unique index already present (from the Mongo shell, or Robo3T, or another client)
>
> MongoDB extension commands to manage data in Azure Cosmos DB’s API for MongoDB | Microsoft Docs
>
>For example:

db.runCommand({
  customAction: "CreateCollection",
  collection: "my_collection",
  shardKey: "my_shard_key",
  offerThroughput: 100,
  indexes: [{key: {_id: 1}, name: "_id_1"}, {key: {a: 1, b: 1}, name:"a_1_b_1", unique: true} ]
})

So now my code looks like this:

func Collection(db *mongo.Database, c string, indices []bson.M) *mongo.Collection {
    ctx, cls := context.WithTimeout(context.Background(), time.Second * 15)
    defer cls()

    if cursor, _ := db.ListCollectionNames(ctx, bson.M{"name": c}); len(cursor) < 1 {
	    cmd := bson.D{{"customAction", "CreateCollection"}, {"collection", c}}
	    if indices != nil {
		    cmd = append(cmd, bson.E{Key: "indexes", Value: indices})
	    }

	    res := db.RunCommand(ctx, cmd)

	    if res.Err() != nil {
		    log.Fatal(res.Err())
	    }
    }

    return db.Collection(c)
}