Protractor (5.4.2) hangs when running shardTestFiles: true

When running protractor without sharding, it runs just fine, the tests are passing or failing, and in the end the webdriver / protractor execution stops.

When trying to run protractor with sharding, the execution works but when all the tests are done, the process hangs, the console doesn't display anything.

I stripped down the config file as much as possible to give more visibility. I'm running protractor using

protractor conf --suite all

Conf file:

'use strict';

require('dotenv').config();
const SpecReporter = require('jasmine-spec-reporter').SpecReporter;

let config = {
    framework: 'jasmine2',
    baseUrl: process.env.CLUSTER_URL,
    rootElement: 'body',

    onPrepare: function () {
        jasmine.getEnv().addReporter(new SpecReporter());
    },

    suites: {
        all: [
            'FoH/customerManagement/UI/*.smoke.spec.js',
            'Other/logo/logo.*.spec.js'
        ]
    },

    capabilities: {
        browserName: 'chrome',
        shardTestFiles: true,
        maxInstances: 2
    }
};

exports.config = config;