Still having this issue - any idea if it is fixed by now ? Exporting for App Store Distribution failed. Please download the logs artifact for more information.

Same problems here. Are you all on Xcode 16.1?

Before switching to the integrated GPU you might need to check if your system even has one, for all mac pro's and most iMacs this is not a valid workaround as these machines just come with discrete GPUs. So if you run Xcode 12.3 on these machines you are required to use the iOS 14.2 Simulators, which work as expected. Ticket filed: FB8942599