RTMS works on developer account but not on Zoom marketplace tester's account (Development mode)

Realtime Media Streams
1

Hi,

We’re building a General App with Real-Time Media Streams (RTMS) for live transcription. Our app is currently in Development mode and a Zoom marketplace reviewer is testing it, so we’re using our Development Client ID / Secret.

Setup

  • General App, User-managed

  • Event Subscription configured with all 5 RTMS events (started/stopped/concurrency limited/near limit/interrupted in Meeting)

  • Webhook URL validated successfully

  • RTMS is triggered via Zoom Apps SDK (zoomSdk.startRTMS()), called when the user clicks our “Start Captions” button (not auto-start on app open)

Issue

  • On my own developer account: everything works perfectly. startRTMS() returns Success, meeting.rtms_started webhook arrives, audio streams, captions work end-to-end.

  • On the marketplace tester’s account: zoomSdk.startRTMS() returns { message: "Success" }, but no meeting.rtms_started webhook is ever delivered to our endpoint. The “App is capturing meeting content” indicator never appears in the Zoom client, and RTMS never actually joins the meeting.

The tester confirmed they regularly test other RTMS apps and those work fine on their account, the issue seems specific to our app. They were testing that on Production env, which had no problems. But when they ask to try it on Development mode, the issue arises. All scopes, event subs, webhooks are same both in Development and Production environment.

What we’ve verified

  • Webhook URL is reachable and validated

  • Event subscription includes meeting.rtms_started

  • Same flow works flawlessly on the developer account

  • Server logs show the webhook simply never arrives for non-developer users (not a 401 or auth error, no delivery attempt at all)

Tester said that someone on zoom developer support team can help by maybe hopping on a quick call.

Thanks!
Ahmet