Data not updated on Production DB - swift

Question

I have a weird situation on my project. I have 2 entities: children and users. Users create children, so on children, I have a reference to their owners and on users I have a list of the children they have created.
When I add a new child to firebase, the user owner of that child has his list of children updated to add that new child.
The thing is: on the staging environment everything works as it should be. But on the production environment, the child is added to the children, but not to the list of children on users.
Both databases have the same rules.
I've got to this project when it was already partially developed, so I can't even find where specifically the user should be updated. It seems to me that when you update a child, the users entity is automagically updated (using breakpoints I could verify it actually happens on the same step). I'm kind of new to Firebase so I am really lost here.
Can anyone try to help me?
Here are the database rules:
{"rules": {
"children": {
"$uid": {
".validate": "newData.hasChildren(['first_name'])",
"date_of_birth": {
".validate": "newData.isString() && newData.val().matches(/^(19|20)\\d\\d-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])$/)"
},
"first_name": {
".validate": "newData.isString() && newData.val().length > 0"
},
"users": {
"$key2": {
".validate": "root.child('users').child($key2).val() != null && newData.isString() && newData.val() == 'parent'"
},
".validate": "newData.hasChildren()"
},
"$other": {
".validate": "false"
},
".read": "data.child('users').child(auth.uid).val() != null",
".write": "data.child('users').child(auth.uid).val() == 'parent' || newData.child('users').child(auth.uid).val() == 'parent'"
}
},
"users": {
".indexOn": [
"email"
],
"$uid": {
".validate": "newData.hasChildren()",
"email": {
".validate": "newData.isString() && newData.val() == auth.token.email"
},
"first_name": {
".validate": "newData.isString()"
},
"is_subscribed": {
".validate": "newData.isBoolean()"
},
"children": {
"$key5": {
".validate": "root.child('children').child($key5).val() != null && newData.isString() && newData.val() == 'parent'"
},
".validate": "newData.hasChildren()"
},
"$other": {
".validate": "false"
},
".read": "auth != null && auth.uid == $uid",
".write": "auth != null && auth.uid == $uid"
}
}
}
}
and the code that adds children to it.
var entityDatabase: DatabaseReference = Database.database().reference().child(“children”).child(did)
entityDatabase.keepSynced(true)
var firstName: String?
var users: [String: String] = [:]
var params: [String: Any] {
var strings: [String: String] = [:]
strings["first_name"] = firstName
let keysToRemove = strings.keys.filter { strings[$0] == "" }
for key in keysToRemove {
strings.removeValue(forKey: key)
}
var dict: [String: Any] = strings
dict["users"] = users
return dict
}
guard let user = Firebase.Auth.auth().currentUser else {
return
}
guard firstName?.isEmpty == false else {
return
}
users[user.uid] = "parent"
entityDatabase.updateChildValues(params) { [weak self] (error, _) in
self?.observe()
guard error == nil else {
return
}
switch self?.updatedImage {
case let image?:
self?.save(image: image, completion: completion)
case nil:
}
}