MongoDB doesn't save document when timestamps are initialized in struct

I am having a very weird issue when trying to save a data in Mongodb by the Rust driver. This is my struct

#[derive(Deserialize, Serialize, Debug)]
struct Info {
 #[serde(rename = "_id", skip_serializing_if = "Option::is_none")]
 id: Option<bson::oid::ObjectId>,
 name: String,
 created_at: i64,
 updated_at: i64,
} 

And this is my actix route handler function

async fn post_request(info: web::Json<Info>, data: web::Data<State>) -> impl Responder {
    let name: &str = &info.name;
    let document = Info {
        id: None,
        name: name.to_string(),
        created_at: Utc::now().timestamp_millis(),
        updated_at: Utc::now().timestamp_millis(),
    };
    // Convert to a Bson instance:
    let serialized_doc = bson::to_bson(&document).unwrap();
    let doc = serialized_doc.as_document().unwrap();
    let collection = data.client.database("test1").collection("users");
    let result = collection.insert_one(doc.to_owned(), None).await.unwrap();
    HttpResponse::Ok().json(result).await
}

And this is my Cargo.toml

[dependencies]
mongodb = { version = "1.1.1", default-features = false, features=["async-std-runtime"] }
actix-web = "3.3.2"
dotenv = "0.15.0"
serde = {version = "1.0.118", features = ["derive"]}
bson = "1.1.0"
chrono = { version = "0.4.19", features = ["serde"] }
futures = "0.3.8"

I am getting the Utc struct by chrono crate. When i am trying to save the data in MongoDB by hitting the route, It doesn't gets saved. But, oddly, when i comment out the created_at and updated_at in struct and handler, it gets saved. If i don't use structs and try to save it as a raw document, by using the doc! macro and storing created_at and updated_at in variables, then also it gets saved, but not by structs. I am new to rust so maybe i am doing something wrong. Please help