I’m experiencing the same issue.
I built a Custom GPT with Actions that works flawlessly from desktop (Chrome) and Android Chrome browser, but fails completely from the official Android ChatGPT app.
The endpoint is functional, has proper CORS configuration, and logs show that no request is ever sent when accessed from the app. From the UI it looks like it’s working, but nothing reaches the server.
As a workaround, I uninstalled the ChatGPT app and accessed it from Chrome on Android — and everything worked perfectly.
This clearly confirms it’s a bug in the Android app and not a backend issue. I hope this gets fixed soon. Let me know if you need logs or a test GPT to reproduce it.