Hi there, So I've been banging my head for the last week, because we have an issue in our app where it's freezing on export while the composition has a AVVideoCompositionCoreAnimationTool as animationTool Before extracting the code to an app I can share, or submit a TSIs, I was wondering if this rings a bell to someone. Basically, we're not doing something too crazy We create an AVAssetExportSession from a composition, some audio and some layers to animate.     func makeExportable(configuration: ExportConfiguration) throws -> AVAssetExportSession {         if let animationLayer {             let rect = CGRect(origin: .zero, size: configuration.videoSize)             let videoAnimationLayer = CALayer()             videoAnimationLayer.frame = rect             let videoLayer = CALayer()             videoLayer.frame = rect             videoAnimationLayer.addSublayer(videoLayer)             videoAnimationLayer.addSublayer(animationLayer)             videoAnimationLayer.isGeometryFlipped = true             let animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer,                                                                     in: videoAnimationLayer)             avVideoComposition.animationTool = animationTool         }         guard             let session = AVAssetExportSession(asset: avComposition,                                                presetName: configuration.avAssetExportPresetName) else {             throw CompositionError.invalidExportSession         }         session.audioMix = audioMix         session.videoComposition = avVideoComposition         return session)     } Then we run await session.export() If we do that multiple times in a row (there are no specific triggers, I can have a 3s video with 40 CALayers or a 30s with 1500 layers, it could happen on the first export or the 20th, ...), then at some point, the app will just have a severe hang with the following stack trace (if I pause the debug session). If ever, I remove the avVideoComposition.animationTool = animationTool line from the export session creation, then the app does not hang... Also, I encounter the issue with the fact that it's crashing on a sim but running fine on a device. Some api_misuse crash (see [here)]. Could this be related, idk...(https://developer.apple.com/forums/thread/133681) Anyway... Completely stuck here, and surprised that such a thing would have an issue on AVFoundation. We're probably not the onliest using CoreAnimation on a video export... Thanks! Marian