Known Issues

Unreal Engine on Mac

Unreal Engine is crashing on Mac version 10.12 (Sierra) or lower with an integrated video card, due to a driver bug. You can resolve this by upgrading to a newer version of Mac, for example, 10.13 (High Sierra).

Using a source checkout with trial packages

All plugins/games that come with Prysm are prebuilt using the latest Unreal Engine version. If you want to run them, you will need to Generate Project Files from your game’s .uproject file and build from source.

Missing Live Views on mobile devices

There is an issue with the live views that causes them to not be rendered on Android and iOS. As a workaround, you can add a black background behind the live view in the html as shown here:

<div style="background:black;">
   <img src="TextureRenderTarget2D'/Game/MapAssets/LiveViews/RenderTargetOnPlayer.RenderTargetOnPlayer'">
</div>

Android linker failure due to missing reference to LowLevelTasks::FTask::ActiveTask symbol

As described in this forum post, when building for android you could hit a linker error:

ld.lld: error: undefined symbol: LowLevelTasks::FTask::ActiveTask

This error is caused by the Engine’s Core module not exporting LowLevelTasks::FTask::ActiveTask symbol and if you are hitting it, it’s most likely due to targeting an Android NDK API Level above android‑28.

To workaround this issue you can change the targeted NDK API Level to android-28 or lower inside the editor settings.

Note

As of UE5.1, the engine’s default NDK API Level is android-26. Unless you have a specific requirement for higher API levels, you generally should not change this setting.

Any changes made to these settings are stored outside the project, inside %LOCALAPPDATA%\Unreal Engine\Engine\Config\UserEngine.ini on Windows, and that makes them persistent and shared between all projects and engine versions.

Missing input for in-world Views on Android

Input for in-world Views requires getting the Mesh data from the GPU so the plugin can determine the position of the input event in our Prysm View. However, this functionality is not supported by UE4’s GLES implementation for Android.

To have a working input for in-world Views on Android, Support UV From Hit Results should be enabled in the Physics Settings.

Note

Enabling the setting will increase the size of your .apk, as Unreal Engine will start storing the UV coordinates for each Mesh.

Missing input for in-world Views using Vulkan rendering

Input for in-world Views requires getting the Mesh data from the GPU, but the Vulkan API does not support this yet, so instead the plugin has to access the CPU data, if it is available.

To have a working input for in-world Views using Vulkan, the Allow CPU Access option should be enabled in the Static Mesh settings of the meshes, used for the in-world Views.

Slow loading of UI resources over HTTP(S)

The slow loading of UI resources over HTTP(S) is due to the default Unreal Engine settings for HTTP, making the download of files over HTTP(S) very slow. Large resources will be affected the most, such as 4K images and video files.

By adding this to the Engine.ini configuration of your project or engine, you can significantly optimize the download speeds:

[HTTP]
HttpThreadActiveFrameTimeInSeconds=0.00001

[HTTP.Curl]
BufferSize=524288

To find out more about this problem and the suggested Engine.ini changes, you can check this related community conversation.

Unreal Memory Insights on XboxOne(GDK) and Scarlett

Due to the intrinsic specifics of V8 (the JavaScript VM that Prysm uses) on the Xbox platforms, currently, it is not possible to utilize the Unreal Memory Insights feature for our plugin.

For this reason, if Prysm detects that memory tracing has been enabled on Xbox platforms, Prysm allocations won’t happen through GMalloc, because in such cases GMalloc is actually the allocator that the Memory Insights feature uses. Instead, we utilize the FPlatformMemory::BaseAllocator API, which returns the default platform allocator without the Memory Insights one acting as an intermediary.

Intrusive assert in XboxCommonPlatformMemory on some Unreal versions

Between Unreal Engine’s 4.27 and 5.3 versions at one point a conditional log (UE_CLOG) was added to the FXboxCommonPlatformMemory::BaseAllocator() definition in the XboxCommonPlatformMemory.cpp file:

FMalloc* FXboxCommonPlatformMemory::BaseAllocator()
{
    UE_CLOG(GMallocInstance, LogInit, Fatal, TEXT("FPlatformMemory::BaseAllocator is not expecting be called multiple times") );

    CreateMallocInstance();
    return GMallocInstance;
}

Epic’s developers later seem to have realized the unnecessary assertion that this produces, so in 5.3 the code was switched to:

FMalloc* FXboxCommonPlatformMemory::BaseAllocator()
{
    if (GMallocInstance != nullptr)
    {
        return GMallocInstance;
    }

    CreateMallocInstance();
    return GMallocInstance;
}

Caution

In case you have encountered this assert, you can just recompile the XboxCommonPlatformMemory.cpp file, using the second code snippet.

Unreal Engine 5.6 issues

Linux deadlock

In Unreal Engine 5.6.0 and 5.6.1 there is a chance that a deadlock may occur with Linux builds, due to these changes done for the Vulkan RHI, where RHI submission and interrupt threads, and timeline semaphore got introduced. Although the commit states these threads should be disabled by default, they are not. It is highly recommended to pre-configure your LinuxEngine.ini and LinuxArm64Engine.ini files to include the same Vulkan configurations that Epic have added for Android:

r.Vulkan.Submission.AllowTimelineSemaphores=0
r.Vulkan.Submission.UseInterruptThread=0
r.Vulkan.Submission.UseSubmissionThread=0
r.Vulkan.RHIThread=1
r.Vulkan.AllowAsyncCompute=0

This should resolve deadlock issues on Linux.

Unreal multiple configuration builds for XboxOne(GDK) and Scarlett

Because delay-loading is not available on these platforms (unless you disable OneCore), for the loading of non-system DLLs to succeed, you need to place them next to the target executable. However, if you are performing a multiple configuration build (e.g. Shipping + Development), since our libraries do not currently have a suffix in the name based on the configuration, you can work around this by setting the Target.ExeBinariesSubFolder in your [ProjectName].Target.cs to the Target.Configuration. This will essentially place the executable and DLLs inside [ProjectDir]/Binaries/PlatformName/Config. Here’s an example snippet:

bOverrideBuildEnvironment = true;
// This will create a Debug/Development/Test/Shipping subdir in ProjectDir/Binaries/PlatformName
ExeBinariesSubFolder = Target.Configuration.ToString();

Caution

Modifying the Target.ExeBinariesSubFolder requires you to set bOverrideBuildEnvironment to true as well.

Unreal Engine 5.8 issues

Vulkan Dynamic Rendering engine bug

In Unreal Engine 5.8.0 the Vulkan Dynamic Rendering feature has been enabled by default. Unfortunately, a bug that was present in the preview version entered the release before the fix could be applied, which can result in some missing elements in certain cases. Until a patch version applies the fix, the workaround for this bug is to disable the Vulkan Dynamic Rendering feature (effectively returning the default behavior as it was pre-UE5.8) by adding the following to your DefaultEngine.ini project config file:

[/Script/Engine.RendererSettings]
r.Vulkan.AllowDynamicRendering=0