I'm having the same type of problem reported on this thread: "Can't get LaunchBox to Open MAME games via RetroArch"
I am just trying to setup my Launchbox 13.6 for Windows 10 for the first time, and am running into the same problem. I can't launch any MAME games using RetroArch from Launchbox. When I try to launch, I see the cursor spin for a few seconds, the hard drive spins up, then nothing.
I had installed RetroArch from LaunchBox successfully under LaunchBox\Emulators\RetroArch\RetroArch.exe, and am able to manually launch RetroArch from Launchbox by right-clicking any game title and selecting "Open RetroArch..." from the popup menu. Once RetroArch is loaded, I can manually run any MAME game from there.
The problem seems to be that LaunchBox just doesn't try to launch RetroArch when launching a game, as RetroArch\logs folder is empty (after turning on Debug logs there). Opening the LaunchBox debug logs, everything looks good, including LaunchBox validating the ROM Is "OK" then the last thing I see before it gives up is:
2023-08-01 08:57:49 AM Unbroken.LaunchBox.Windows.Desktop.ViewModels.MainViewModel.window.Deactivated Start
2023-08-01 08:57:49 AM Unbroken.LaunchBox.Windows.Desktop.ViewModels.MainViewModel.window.Deactivated Before Pause Video
2023-08-01 08:57:49 AM Unbroken.LaunchBox.Windows.Desktop.ViewModels.MainViewModel.window.Deactivated Completed
But when I re-opened the LaunchBox log a minute later, it seems to have flushed a few error messages (see attached), immediately below the statements above, that may be related with the original launch request (not 100% sure, due to slow flushing of logs, and low resolution of timestamps)...
2023-08-01 08:58:48 AM FIRST CHANCE EXCEPTION: Unable to read data from the transport connection: The I/O operation has been aborted because of either a thread exit or an application request..
at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource<System.Int32>.GetResult(Int16 token)
at System.Net.Security.SslStream.ReadAsyncInternal[TIOAdapter](TIOAdapter adapter, Memory`1 buffer)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
2023-08-01 08:58:48 AM FIRST CHANCE CONTINUED INNER EXCEPTION: The I/O operation has been aborted because of either a thread exit or an application request.
The problem is 100% reproducible on any MAME game, when attempting to use the correct "MAME Current" core (mame_libreto.dll) which works from RetroArch directly.
Debug 2023-08-01 08-57-30 AM.log