NestJs/Graphql: "CustomObject" defined in resolvers, but not in schema

Question

I'm having an issue after updating nest/core/common/graphql, in which a single type definition is not showing up in the schema. I'm consistently getting an error that it doesn't exist, though I can't find any difference between it's definition and all of the others in my application. It could totally be some ridiculous thing I am overlooking, but I am getting no other errors. I've attached the type def below. If I understood how this was being generated with the new "autoSchemaFile: true," syntax I might be able to track down where the issue is coming from.

import { Field, ObjectType, ID } from '@nestjs/graphql';
import { ObjectID } from 'mongodb';


@ObjectType()
export class CustomObject {
  @Field(type => ID, { nullable: true })
  id?: ObjectID;

  @Field(type => String, { nullable: true })
  otherField?: string;
}