XR Session Crashes Frequently

[AJTech2002]

Error:

-[MTLDebugTexture setPurgeableState:]:832: failed assertion `Set Purgeable Stage Validation Cannot set purgeability state to volatile while resource is in use by a command buffer.'

The following error is thrown in the XCode console, referring to line 936 within xr/Source/ARKit/XR.mm for the following lines:

[currentCommandBuffer addCompletedHandler:^(id<MTLCommandBuffer>) {
                    if (cameraTextureY != nil) {
                        [cameraTextureY setPurgeableState:MTLPurgeableStateEmpty];
                    }

                    if (cameraTextureCbCr != nil) {
                        [cameraTextureCbCr setPurgeableState:MTLPurgeableStateEmpty];
                    }
                }];

Originally I was getting this error as soon as the WebXR session launched however we tried replacing it with the following code which reduces the frequency of the crash & allows us to run the XR session however it still occurs intermittently:

[currentCommandBuffer addCompletedHandler:^(id<MTLCommandBuffer>) {
                    id<MTLCommandBuffer> cleanupCommandBuffer = [commandQueue commandBuffer];

                    [cleanupCommandBuffer addCompletedHandler:^(id<MTLCommandBuffer>) {
                        if (cameraTextureY && cameraTextureY.allocatedSize > 0) {
                            NSLog(@"Setting cameraTextureY to purgeable.");
                            [cameraTextureY setPurgeableState:MTLPurgeableStateEmpty];
                        }
                        if (cameraTextureCbCr && cameraTextureCbCr.allocatedSize > 0) {
                            NSLog(@"Setting cameraTextureCbCr to purgeable.");
                            [cameraTextureCbCr setPurgeableState:MTLPurgeableStateEmpty];
                        }
                    }];

                    [cleanupCommandBuffer commit];
                }];

This occurs while within an XR Session and can occur for a variety of reasons such as loading a large 3D model while in session.

It seems to occur at random, however the pattern is this occurs whenever there is a significant frame drop. Once this error occurs the XR session freezes.

Platform: iOS 17.6