Bug: Create Activity API returns empty body

[jalber]

The majority of my create activity API requests succeed, except for one user who continues to see empty body responses.

API: POST /api/v3/activities

Request body:

{
external_id: 'blurwsuuid:398B5EDB-A11F-41D9-86A7-D67AF5973642',
type: 'Run',
trainer: 1,
workout_type: 3,
name: 'App Name: Afternoon Treadmill Run',
description: 'Full Potential Unlock — 30 min\nhttps://www.appwebsite.com',
start_date: '2024-09-04T18:03:25.945Z',
elapsed_time: 1868.2,
distance: 3865.9493681170975,
calories: 248.20267505699672,
has_heartrate: true,
average_heartrate: 148.09549154564937,
max_heartrate: 173
}

Expected response body:

{
id: ...
}

Actual response body:

(none)

[jalber]

This is continuing to happen and contradicts the documentation. Can anyone at Strava take a look?
Response status code: 201
Response body: (empty)