Winston transport for Loggly not working consistently

I have Winston set up with 3 transports: Console, File, and Loggly (using https://github.com/loggly/winston-loggly-bulk).

While the Console and File transports log properly, my Loggly transport only logs my initial "Server listening on port 3001" log and nothing else, and I don't understand why.

logger-utils.ts:

import * as winston from 'winston';
import { Loggly } from 'winston-loggly-bulk';

export const createLogger = () => {
  return winston.createLogger({
    format: winston.format.combine(
      winston.format.errors({ stack: true }),
      winston.format.timestamp({
        format: 'YYYY-MM-DD HH:mm:ss ZZ',
      }),
      winston.format.json(),
    ),
    transports: [
      new winston.transports.Console({
        level: process.env.LOGGING_LEVEL,
      }),
      new winston.transports.File({ filename: `logs/my-app.log` }),
      new Loggly({
        token: '<token>',
        subdomain: '<subdomain>',
        tags: ['Winston-NodeJS'],
        json: true,
      }),
    ],
  });
};

logger.ts:

import { createLogger } from './logger-utils';

const logger = createLogger();

export default logger;

server.ts:

import app from './modules/app/app';
import logger from './core/logger/logger';

app.listen(PORT, () => {
  logger.info(`Server listening on port ${3001}`);
});

app.middleware.ts:

import logger from '../../core/logger/logger';

export const initializeApp = async (ctx: AppContext) => {
  logger.info('initializeApp', { ctx });
  ....

So, I start the server and run through a flow, and when I check the Console and File I see that it logs both the messages in server.ts and app.middleware.ts but when I check my Loggly dashboard I only see the log from server.ts.

I feel like I'm missing something incredibly obvious but I don't understand why it won't log my info in app.middleware.ts despite logging my stuff in server.ts, and it makes even less sense when I consider that both Console and File transports are logging everything correctly.

Any ideas on how to fix this issue so that my Loggly transport works like my other transports?

ctx object has circular reference inside and probably serialization failed at the Loggly end. Logging without the ctx object should fix the issue.