Frame-locked sequencer intermittently triggers notify state end event

void FAnimMontageInstance::Advance(float DeltaTime, struct FRootMotionMovementParams* OutRootMotionParams, bool bBlendRootMotion)
{
...
				// Delegate has to be called last in this loop
				// so that if this changes position, the new position will be applied in the next loop
				// first need to have event handler to handle it
				// Save off position before triggering events, in case they cause a jump to another position
				const float PositionBeforeFiringEvents = Position;
 
				const bool bHaveNotMoved = (SubStepResult == EMontageSubStepResult::NotMoved);	//work around : add line
				if( bHaveMoved || bHaveNotMoved )	//work around : Trigger the event even if the cursor did not move.
				{
					// Save position before firing events.
					if (!bInterrupted)
					{
						// Must grab a reference on the stack in case "this" is deleted during iteration
						TWeakObjectPtr<UAnimInstance> AnimInstanceLocal = AnimInstance;
 
						HandleEvents(PreviousSubStepPosition, Position, BranchingPointMarker);
 
						// Break out if we no longer have active montage instances. This may happen when we call UninitializeAnimation from a notify
						if (AnimInstanceLocal.IsValid() && AnimInstanceLocal->MontageInstances.Num() == 0)
						{
							return;
						}
					}
				}