Unreal Engine Issues
Unreal Engine Issues
Notifies placed on the first frame of a montage using root motion don't fire
UE - Runtime - Animation - Aug 10, 2026This is a regression in 5.8 caused by 47265321. It's because we now perform the montage update and dispatch the queued notifies via CharacterMovementComponent::TickCharacterPose. But that all hap ...
Root motion extraction fails on blendspaces with bShouldMatchSyncPhases set
UE - Runtime - Animation - Aug 7, 2026There’s a bug with the bShouldMatchSyncPhases codepath in UBlendSpace::TickAssetPlayer. That codepath calls ResetBlendSamples to give a deterministic output when advancing time on the animations ow ...
BlendSpace Loop Boundary Produces Inconsistent Sync Marker Data andTriggers an AnimSequence Follower Assertion
UE - Runtime - Animation - Jul 22, 2026Summary In UE 5.7.4, when a looping BlendSpace with Match Sync Phases enabled plays as a SyncGroup Leader and crosses its loop boundary during a transition to an external AnimSequenceFollower in th ...
Deadlock during cooking or editor in URigHierarchyController::AddElement on task thread while GarbageCollection occurs on gamethread.
UE - Runtime - Animation - Apr 15, 2026In URigHiearchyController::AddElement (and other functions), arbitrary delegate code is called while holding Hierarchy->ElementsLock, through the Notify function. URigHierarchy::AddReferencedObject ...
AnimNotify serialization crash in editor
UE - Runtime - Animation - Mar 15, 2026The crash is caused by changing the variable type of an AnimNotify that is already referenced by a montage. This issue cannot be reproduced in 5.6. ...
Frame-locked sequencer intermittently triggers notify state end event
UE - Runtime - Animation - Mar 10, 2026Frame-locked Sequencers can occasionally produce frames with a zero delta time due to frame number truncation. When this occurs, if the animation cursor is within the range of a Notify State that is ...
Clicking on the timeline to move the playhead of the Persona animation viewer does not move the playhead.
UE - Runtime - Animation - Mar 6, 2026Scrubbing is the only way to move the playhead. ...
anim notify states are triggered when updating thumbnails
UE - Runtime - Animation - Feb 19, 2026The issue is that FAnimationSequenceThumbnailScene::SetAnimation calls referesh bone transforms which will trigger notify states present at the midpoint of the animation (as the thumbnail code sets ...
Missing logging or error when applying an anim instance to a skeleton that the anim instance doesn't match.
UE - Runtime - Animation - Feb 9, 2026Currently, we detect whether an anim instance is supported by the skeletal mesh and, if it isn't, unreference the instance, but we don't error or warn the user that this happened. This leads to conf ...
Changing the ComponentClass of a ACharacter twice and trying to set a SkeletalMeshAsset crashes the engine
UE - Runtime - Animation - Jan 22, 2026Changing the ComponentClass of a ACharacter twice and trying to set a SkeletalMeshAsset crashes the engine with a "Cannot replace existing object of a different class" message. The conditions to re ...