I've created an unmodified project using the HandheldAR template, and deployed it to an iPad after building via a remote Mac build server (while it's a Blueprint-only project, a Mac is still required to build AR application).
Project builds and deploys to the device without errors, and certificates report that they're valid, but when I attempt to launch it on the iPad, the default project splashscreen appears, and then the device dumps back to the home screen. Application still appears as a running app, but if I attempt to switch back to it, it just bounces back to the home screen.
Other Blueprint-only UE4 projects deployed from the same machine work as expected on the device.
From the log below, it appears that /Script/AugmentedReality failed to load.
[2018.08.03-17.56.36:622][ 0]LogAIModule: Creating AISystem for world HandheldARBlankMap [2018.08.03-17.56.36:625][ 0]LogStreaming: Error: Couldn't find file for package /Script/AugmentedReality requested by async loading code. NameToLoad: /Script/AugmentedReality [2018.08.03-17.56.36:625][ 0]LogStreaming: Error: Found 1 dependent packages... [2018.08.03-17.56.36:625][ 0]LogStreaming: Error:
/Game/HandheldARBP/Blueprints/GameFramework/BP_ARPawn [2018.08.03-17.56.36:628][ 0]LogStreaming: Error: ****DumpDependencies [Dependencies]: [2018.08.03-17.56.36:628][ 0]LogStreaming: Error: Export 1 /Game/HandheldARBP/D_ARSessionConfig.D_ARSessionConfig [2018.08.03-17.56.36:628][ 0]LogStreaming: Error: Linker is ../../../HandheldAR/Content/HandheldARBP/D_ARSessionConfig.uasset [2018.08.03-17.56.36:628][ 0]LogStreaming: Error: Dep S_BEFORE_C Import 1 /Script/AugmentedReality.ARSessionConfig [2018.08.03-17.56.36:628][ 0]LogStreaming: Error: Dep S_BEFORE_C Import 0
/Script/AugmentedReality.Default__ARSessionConfig [2018.08.03-17.56.36:628][ 0]LogStreaming: Error: Missing Dependency, request for /Script/AugmentedReality.ARSessionConfig but it hasn't been created yet. [2018.08.03-17.56.36:628][ 0]LogStreaming: Error: Could not find class ARSessionConfig to create D_ARSessionConfig [2018.08.03-17.56.36:633][ 0]LogProperty: Error: Struct type unknown for property 'StructProperty /Game/HandheldARBP/Blueprints/UI/BP_DebugMenu.BP_DebugMenu_C:UpdateDebugMenuInfo.CallFunc_GetARSessionStatus_ReturnValue'; perhaps the USTRUCT() was renamed or deleted? [2018.08.03-17.56.36:633][ 0]LogProperty: Error: Struct type unknown for property 'StructProperty /Game/HandheldARBP/Blueprints/UI/BP_DebugMenu.BP_DebugMenu_C:ToggleARMode.CallFunc_GetARSessionStatus_ReturnValue'; perhaps the USTRUCT() was renamed or deleted? [2018.08.03-17.56.36:633][ 0]LogProperty: Error: Struct type unknown for property 'StructProperty /Game/HandheldARBP/Blueprints/UI/BP_DebugMenu.BP_DebugMenu_C:InitializeDebugButtonStates.CallFunc_GetARSessionStatus_ReturnValue'; perhaps the USTRUCT() was renamed or deleted? [2018.08.03-17.56.36:634][ 0]LogProperty: Error: Struct type unknown for property 'StructProperty /Game/HandheldARBP/Blueprints/GameFramework/BP_ARPawn.BP_ARPawn_C:ExecuteUbergraph_BP_ARPawn.CallFunc_LineTraceTrackedObjects_ReturnValue.CallFunc_LineTraceTrackedObjects_ReturnValue'; perhaps the USTRUCT() was renamed or deleted? [2018.08.03-17.56.36:639][ 0]LogLoad: Game class is 'BP_ARGameMode_C' [2018.08.03-17.56.36:640][ 0]LogWorld: Bringing World /Game/HandheldARBP/Maps/HandheldARBlankMap.HandheldARBlankMap up for play (max tick rate 0) at 2018.08.03-10.56.36 [2018.08.03-17.56.36:640][ 0]LogWorld: Bringing up level for play took: 0.000401 [2018.08.03-17.56.36:640][ 0]LogGameMode: FindPlayerStart: PATHS NOT DEFINED or NO PLAYERSTART with positive rating [2018.08.03-17.56.36:642][ 0]LogUMG: Display: Widget Class BP_MainMenu_C - Loaded Fast Template. [2018.08.03-17.56.36:643][ 0]LogUMG: Display: Widget Class BP_DebugMenu_C - Loaded Fast Template. [2018.08.03-17.56.36:644][ 0]LogScript: Warning: Accessed None BP_DebugMenu_C /Engine/Transient.GameEngine_0:GameInstance_0.BP_DebugMenu_C_0 Function /Game/HandheldARBP/Blueprints/UI/BP_DebugMenu.BP_DebugMenu_C:InitializeDebugButtonStates:001C [2018.08.03-17.56.36:644][ 0]LogScript: Warning: Script call stack: Function /Game/HandheldARBP/Blueprints/UI/BP_DebugMenu.BP_DebugMenu_C:Construct Function /Game/HandheldARBP/Blueprints/UI/BP_DebugMenu.BP_DebugMenu_C:ExecuteUbergraph_BP_DebugMenu Function /Game/HandheldARBP/Blueprints/UI/BP_DebugMenu.BP_DebugMenu_C:InitializeDebugButtonStates[2018.08.03-17.56.36:644][ 0]LogOutputDevice: Warning:
Script Stack: BP_DebugMenu_C.InitializeDebugButtonStates BP_DebugMenu_C.ExecuteUbergraph_BP_DebugMenu BP_DebugMenu_C.Construct BP_ARPawn_C.ExecuteUbergraph_BP_ARPawn BP_ARPawn_C.ReceiveBeginPlay
iPad specs:
It appears that the answer was simply that the Apple ARKit plugin was not enabled. Enabling it and rebuilding corrected the issue.