Intel macOS build stuck on red screen when AGS is enabled unless Epic Launcher or Unreal Editor is running

Hello Team,

We are investigating a startup issue in our Unreal Engine 5.5.4 macOS build. The issue reproduces only on Intel MacBook Pro machines. We have not observed it on non-Intel Macs so far.

Problem:

When AGS - Automatic graphics switching is enabled, the packaged macOS build gets stuck on a red screen during initialization/startup. The app does not proceed to the expected flow. In the reproduced logs, initialization reaches the early game/client startup path, then the app eventually exits with Mac GracefulTerminationHandler.

Important observation:

The issue is not reproducible if Epic Games Launcher or Unreal Editor is already running in the background. With AGS enabled and Epic Launcher/Unreal Editor open, the same build starts correctly. If Epic Launcher/Unreal Editor is closed, the issue reproduces again.

Current test matrix:

1. AGS disabled — issue is not reproduced.

2. AGS enabled + Epic Launcher/Unreal Editor closed — issue is reproduced.

3. AGS enabled + Epic Launcher/Unreal Editor opened in background — issue is not reproduced.

4. Reproduced on two Intel MacBook Pro machines.

Environment:

- Unreal Engine: 5.5.4

- Platform: macOS

- Architecture: x64 / Intel

- Build configuration: Development

- Example device: Intel MacBook Pro, Radeon Pro GPU

I attached VeryVerbose initialization logs for reproduced and non-reproduced cases.

Could you please help us understand what Epic Launcher or Unreal Editor might initialize/provide on Intel macOS that changes this behavior? We would also appreciate suggestions on additional logs, command-line flags, macOS diagnostics, or AGS-related checks that could help isolate the root cause.

Thank you.

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Quick update: we found that the issue is related to Sentry initialization.

I added a temporary -NoSentry flag that skips our manual call to

SentrySubsystem->InitializeWithSettings()

Result:

  • Sentry enabled: issue reproduces on Intel macOS with AGS enabled.
  • -NoSentry: issue is not reproduced.

So the red-screen startup hang seems to be triggered during Sentry initialization, but only on Intel Macs and only when Epic Launcher / Unreal Editor is not running in the background.

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Quick update: We decided to disable Sentry for Intel Mac devices which helped to get rid of the issue.

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Interesting thanks for the update. I’ll forward this to someone on our platform Team.

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