UE 5.6.1: Why is NotifyBegin/NotifyEnd constantly being called in my anim notify state on the server?

Development Programming & Scripting
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I’m running a dedicated server and one client. From the client, I trigger an animation montage containing an anim notify state on my character to play on both the client and dedicated server. NotifyBegin and NotifyEnd are continually called only on the dedicated server instance for the duration of the montage.

The flow is as follows:

  1. UCharacterMovementComponent:ServerMovePacked is called on the server when processing network events. This leads to UCharacterMovementComponent::MoveAutonomous being called followed by UAnimInstance::TriggerAnimNotifies which triggers NotifyBegin on the anim notify state.
  2. UCharacterMovementComponent::MoveAutonomous then calls UAnimInstance::ClearQueuedAnimEvents which clears out the anim instance NotifyQueue.
  3. USkeletalMeshComponent::FinalizeBoneTransform is called on the server during an animation update. This leads to UAnimInstance::TriggerAnimNotifiescalling the NotifyEnd() function of my anim notify state because NotifyQueue was cleared earlier from step 2.

My character isn’t even moving the entire time so I don’t understand why the server is processing the server move. Even if it were moving,NotifyBegin and NotifyEnd are still continually called on the server.

Is this always expected behavior on the server? Should I never be playing anim notify states on the server?

EDIT 1: Confirmed this is not an issue in UE 5.5.4. The notifies are played correctly, and UAnimInstance::ClearQueuedAnimEventsis not present in the code base. Will try to repro in a test project and submit a bug report.

EDIT 2: Already reported in Unreal Engine Issues and Bug Tracker (UE-308913)