Custom mutation is not generating models on iOS

### Before opening, please confirm:

- [X] I have installed the latest version of the Amplify CLI (see above), and confirmed that the issue still persists.
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-cli/issues?q=is%3Aissue+).
- [X] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-cli/blob/master/CONTRIBUTING.md#bug-reports).
- [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

### How did you install the Amplify CLI?

npm

### If applicable, what version of Node.js are you using?

v15.5.1

### Amplify CLI Version

6.3.0

### What operating system are you using?

Mac

### Amplify Categories

auth, api

### Amplify Commands

codegen

### Describe the bug

When adding a custom mutation the amplify cli for iOS does not generate models for them.

### Expected behavior

I was expecting that models for all operations would be created automatically. The folder only contains models for `model`.

### Reproduction steps

1. Add a custom mutation
2. Apply the resolvers
3. Update the CustomResources.json
4. Push

### GraphQL schema(s)

```graphql
type Mutation {
batchCreateEvents(events: [CreateEventInput]): [Event]
}

type Event
@model
@auth(rules: [{ allow: owner, ownerField: "owner" }]) {
id: ID!
owner: String
}

```

### Log output

```
# Put your logs below this line

```

### Additional information

_No response_