Area: CoreML / Machine Learning Describe the issue: On iOS 26.4, calling MLModel(contentsOf:configuration:) to load an .mlpackage model hangs indefinitely and eventually kills the app via watchdog. The same model loads and runs inference successfully in under 1 second on iOS 26.3.1. The hang occurs inside eort_eo_compiler_compile_from_ir_program (espresso) during on-device AOT recompilation triggered by MLE5ProgramLibraryOnDeviceAOTCompilationImpl createProgramLibraryHandleWithRespecialization:error:. A C++ exception (__cxa_throw) is thrown inside libBNNS.dylib during the exception unwind, which then hangs inside __cxxabiv1::dyn_cast_slow and __class_type_info::search_below_dst. Swift's try/catch does not catch this — the exception originates in C++ and the process hangs rather than terminating cleanly. Setting config.computeUnits = .cpuOnly does not resolve the issue. MLE5ProgramLibrary initialises as shared infrastructure regardless of compute units. Steps to reproduce: Create an app with an .mlpackage CoreML model using the MLE5/espresso backend Call MLModel(contentsOf: modelURL, configuration: config) at runtime Run on a device on iOS 26.3.1 — loads successfully in <1 second Update device to iOS 26.4 — hangs indefinitely, app killed by watchdog after 60–745 seconds Expected behaviour: Model loads successfully, or throws a catchable Swift error on failure. Actual behaviour: Process hangs in MLE5ProgramLibrary.lazyInitQueue. App killed by watchdog. No Swift error thrown. Full stack trace at point of hang: Thread 1 Queue: com.apple.coreml.MLE5ProgramLibrary.lazyInitQueue (serial) frame 0: __cxxabiv1::__class_type_info::search_below_dst libc++abi.dylib frame 1: __cxxabiv1::(anonymous namespace)::dyn_cast_slow libc++abi.dylib frame 2: ___lldb_unnamed_symbol_23ab44dd4 libBNNS.dylib frame 23: eort_eo_compiler_compile_from_ir_program espresso frame 24: -[MLE5ProgramLibraryOnDeviceAOTCompilationImpl createProgramLibraryHandleWithRespecialization:error:] CoreML frame 25: -[MLE5ProgramLibrary _programLibraryHandleWithForceRespecialization:error:] CoreML frame 26: __44-[MLE5ProgramLibrary prepareAndReturnError:]_block_invoke CoreML frame 27: _dispatch_client_callout libdispatch.dylib frame 28: _dispatch_lane_barrier_sync_invoke_and_complete libdispatch.dylib frame 29: -[MLE5ProgramLibrary prepareAndReturnError:] CoreML frame 30: -[MLE5Engine initWithContainer:configuration:error:] CoreML frame 31: +[MLE5Engine loadModelFromCompiledArchive:modelVersionInfo:compilerVersionInfo:configuration:error:] CoreML frame 32: +[MLLoader _loadModelWithClass:fromArchive:modelVersionInfo:compilerVersionInfo:configuration:error:] CoreML frame 45: +[MLModel modelWithContentsOfURL:configuration:error:] CoreML frame 46: @nonobjc MLModel.__allocating_init(contentsOf:configuration:) GKPersonalV2 frame 47: MDNA_GaitEncoder_v1_3.__allocating_init(contentsOf:configuration:) frame 48: MDNA_GaitEncoder_v1_3.__allocating_init(configuration:) frame 50: GaitModelInference.loadModel() frame 51: GaitModelInference.init() iOS version: Reproduced on iOS 26.4. Works correctly on iOS 26.3.1. Xcode version: 26.2 Device: iPhone (model used in testing) Model format: .mlpackage

I have created a simple scene in reality composer (composer not composer pro). It contains just a cube and text item. I convert this to usdz file and load it into a Arkit swift app. Since ios 18/xcode 16 - the "text" element is not displayed at all. The cube is displayed, anchors correctly and can be moved etc.... The output from usdchecker ➜ Desktop usdchecker GKTUHR1.6.3.usdz -v --arkit Opening GKTUHR1.6.3.usdz Checking layer <GKTUHR1.6.3.usdz>. Checking package <GKTUHR1.6.3.usdz> Checking prim </Root>. Checking prim </Root/Scenes>. Checking prim </Root/Scenes/Scene>. Checking prim </Root/Scenes/Scene/Gravity>. Checking prim </Root/Scenes/Scene/sceneGroundPlane>. Checking prim </Root/Scenes/Scene/sceneGroundPlane/physicsMaterial>. Checking prim </Root/Scenes/Scene/Children>. Checking prim </Root/Scenes/Scene/Children/hello>. Checking prim </Root/Scenes/Scene/Children/hello/Generated>. Checking prim </Root/Scenes/Scene/Children/hello/Generated/Text>. Checking prim </Root/Scenes/Scene/Children/hello/Generated/Text/Material>. Checking prim </Root/Scenes/Scene/Children/hello/Generated/Text/Material/PBRShader>. Checking shader </Root/Scenes/Scene/Children/hello/Generated/Text/Material/PBRShader>. Checking prim </Root/Scenes/Scene/Children/hello/Children>. Checking prim </Root/Scenes/Scene/Children/Box>. Checking prim </Root/Scenes/Scene/Children/Box/Generated>. Checking prim </Root/Scenes/Scene/Children/Box/Generated/Mesh0>. Checking prim </Root/Scenes/Scene/Children/Box/Generated/Mesh0/Mesh0>. Checking prim </Root/Scenes/Scene/Children/Box/Generated/Mesh0/Material>. Checking prim </Root/Scenes/Scene/Children/Box/Generated/Mesh0/Material/PBRShader>. Checking shader </Root/Scenes/Scene/Children/Box/Generated/Mesh0/Material/PBRShader>. Checking prim </Root/Scenes/Scene/Children/Box/Children>. Checking prim </Root/Scenes/Scene/Children/Box/PhysicsMaterial_Box>. Found material bindings but no MaterialBindingAPI applied on the prim </Root/Scenes/Scene/sceneGroundPlane>. (fails 'MaterialBindingAPIAppliedChecker') Found material bindings but no MaterialBindingAPI applied on the prim </Root/Scenes/Scene/Children/hello/Generated/Text>. (fails 'MaterialBindingAPIAppliedChecker') Found material bindings but no MaterialBindingAPI applied on the prim </Root/Scenes/Scene/Children/Box>. (fails 'MaterialBindingAPIAppliedChecker') Found material bindings but no MaterialBindingAPI applied on the prim </Root/Scenes/Scene/Children/Box/Generated/Mesh0>. (fails 'MaterialBindingAPIAppliedChecker') Failed!