I'm having a strange issue when using an AmbientSoundSimpleToggleable attached to an InterpActor. I have a sound and an object that needs to become visible/audible at a certain point in the level. The problem is that a Toggle Hidden action in kismet appears to disable the ambient sound.

To reproduce, create an InterpActor and an AmbientSoundSimpleToggleable. Set the InterpActor to be the base of the AmbientSound and set Auto Play to false. Create a kismet sequence that toggles the sound on at level load. Create a toggle hidden with the InterpActor as the target and Toggle Based Actors checked. Create a Matinee or a delay or something to call the UnHide input at a later time. This will cause the sound to play on level load, then stop playing when the actor becomes visible.

Here is a snippet of the kismet sequence I used:
Code:
Begin Object Class=SeqAct_ToggleHidden Name=SeqAct_ToggleHidden_0
   bToggleBasedActors=True
   InputLinks(0)=(DrawY=117,OverrideDelta=14)
   InputLinks(1)=(DrawY=138,OverrideDelta=35)
   InputLinks(2)=(DrawY=159,OverrideDelta=56)
   OutputLinks(0)=(DrawY=138,OverrideDelta=35)
   VariableLinks(0)=(LinkedVariables=(SeqVar_Object'SeqVar_Object_31'),DrawX=774,OverrideDelta=16)
   VariableLinks(1)=(DrawX=825,OverrideDelta=76)
   EventLinks(0)=(DrawX=874,OverrideDelta=119)
   ObjInstanceVersion=1
   ParentSequence=Sequence'Main_Sequence'
   ObjPosX=736
   ObjPosY=80
   DrawWidth=173
   DrawHeight=109
   Name="SeqAct_ToggleHidden_0"
   ObjectArchetype=SeqAct_ToggleHidden'Engine.Default__SeqAct_ToggleHidden'
End Object
Begin Object Class=SeqVar_Object Name=SeqVar_Object_30
   ObjValue=AmbientSoundSimpleToggleable'AmbientSoundSimpleToggleable_10'
   ObjInstanceVersion=1
   ParentSequence=Sequence'Main_Sequence'
   ObjPosX=472
   ObjPosY=560
   DrawWidth=32
   DrawHeight=32
   Name="SeqVar_Object_30"
   ObjectArchetype=SeqVar_Object'Engine.Default__SeqVar_Object'
End Object
Begin Object Class=SeqEvent_LevelLoaded Name=SeqEvent_LevelLoaded_2
   MaxWidth=136
   OutputLinks(0)=(Links=((LinkedOp=SeqAct_Interp'SeqAct_Interp_0'),(LinkedOp=SeqAct_Toggle'SeqAct_Toggle_4')),DrawY=269,OverrideDelta=14)
   OutputLinks(1)=(DrawY=290,OverrideDelta=35)
   OutputLinks(2)=(DrawY=311,OverrideDelta=56)
   ObjInstanceVersion=3
   ParentSequence=Sequence'Main_Sequence'
   ObjPosX=72
   ObjPosY=200
   DrawWidth=137
   Name="SeqEvent_LevelLoaded_2"
   ObjectArchetype=SeqEvent_LevelLoaded'Engine.Default__SeqEvent_LevelLoaded'
End Object
Begin Object Class=SeqAct_Toggle Name=SeqAct_Toggle_4
   InputLinks(0)=(DrawY=453,OverrideDelta=14)
   InputLinks(1)=(DrawY=474,OverrideDelta=35)
   InputLinks(2)=(DrawY=495,OverrideDelta=56)
   OutputLinks(0)=(DrawY=474,OverrideDelta=35)
   VariableLinks(0)=(LinkedVariables=(SeqVar_Object'SeqVar_Object_30'),DrawX=526,OverrideDelta=16)
   VariableLinks(1)=(DrawX=577,OverrideDelta=76)
   EventLinks(0)=(DrawX=626,OverrideDelta=119)
   ObjInstanceVersion=1
   ParentSequence=Sequence'Main_Sequence'
   ObjPosX=488
   ObjPosY=416
   DrawWidth=173
   DrawHeight=109
   Name="SeqAct_Toggle_4"
   ObjectArchetype=SeqAct_Toggle'Engine.Default__SeqAct_Toggle'
End Object
Begin Object Class=SeqAct_Interp Name=SeqAct_Interp_0
   InputLinks(0)=(DrawY=118,OverrideDelta=15)
   InputLinks(1)=(DrawY=140,OverrideDelta=37)
   InputLinks(2)=(DrawY=162,OverrideDelta=59)
   InputLinks(3)=(DrawY=184,OverrideDelta=81)
   InputLinks(4)=(DrawY=206,OverrideDelta=103)
   OutputLinks(0)=(DrawY=125,OverrideDelta=22)
   OutputLinks(1)=(DrawY=162,OverrideDelta=59)
   OutputLinks(2)=(Links=((LinkedOp=SeqAct_ToggleHidden'SeqAct_ToggleHidden_0',InputLinkIdx=1)),LinkDesc="Unhide",DrawY=199,OverrideDelta=96)
   VariableLinks(0)=(LinkedVariables=(InterpData'InterpData_1'),DrawX=523,OverrideDelta=20)
   VariableLinks(1)=(ExpectedType=Class'Engine.SeqVar_Object',LinkDesc="NewGroup",MinVars=0,DrawX=588,OverrideDelta=67)
   ObjInstanceVersion=2
   ParentSequence=Sequence'Main_Sequence'
   ObjPosX=488
   ObjPosY=80
   DrawWidth=154
   DrawHeight=157
   Name="SeqAct_Interp_0"
   ObjectArchetype=SeqAct_Interp'Engine.Default__SeqAct_Interp'
End Object
Begin Object Class=InterpData Name=InterpData_1
   Begin Object Class=InterpGroup Name=InterpGroup_0
      Begin Object Class=InterpTrackEvent Name=InterpTrackEvent_0
         EventTrack(0)=(Time=3.000590,EventName="Unhide")
         Name="InterpTrackEvent_0"
         ObjectArchetype=InterpTrackEvent'Engine.Default__InterpTrackEvent'
      End Object
      InterpTracks(0)=InterpTrackEvent'InterpTrackEvent_0'
      GroupName="NewGroup"
      GroupColor=(B=190,G=0,R=147,A=255)
      Name="InterpGroup_0"
      ObjectArchetype=InterpGroup'Engine.Default__InterpGroup'
   End Object
   Begin Object Class=InterpCurveEdSetup Name=InterpCurveEdSetup_2
      Name="InterpCurveEdSetup_2"
      ObjectArchetype=InterpCurveEdSetup'Engine.Default__InterpCurveEdSetup'
   End Object
   InterpGroups(0)=InterpGroup'InterpGroup_0'
   CurveEdSetup=InterpCurveEdSetup'InterpCurveEdSetup_2'
   SelectedFilter=InterpFilter'Engine.Default__InterpData:FilterAll'
   ObjInstanceVersion=1
   ParentSequence=Sequence'Main_Sequence'
   ObjPosX=488
   ObjPosY=280
   DrawWidth=32
   DrawHeight=32
   Name="InterpData_1"
   ObjectArchetype=InterpData'Engine.Default__InterpData'
End Object
Begin Object Class=SeqVar_Object Name=SeqVar_Object_31
   ObjValue=InterpActor'InterpActor_0'
   ObjInstanceVersion=1
   ParentSequence=Sequence'Main_Sequence'
   ObjPosX=744
   ObjPosY=224
   DrawWidth=32
   DrawHeight=32
   Name="SeqVar_Object_31"
   ObjectArchetype=SeqVar_Object'Engine.Default__SeqVar_Object'
End Object
Begin Object Class=SequenceFrameWrapped Name=SequenceFrameWrapped_0
   SizeX=541
   SizeY=384
   ObjInstanceVersion=1
   ParentSequence=Sequence'Main_Sequence'
   ObjPosX=424
   ObjPosY=16
   ObjComment="After 3 seconds, this will unhide the box and all of its children.  AmbientSoundSimpleToggleable_10 gets turned off when this happens.  This does not happen if it's set to Auto Play"
   Name="SequenceFrameWrapped_0"
   ObjectArchetype=SequenceFrameWrapped'Engine.Default__SequenceFrameWrapped'
End Object
Some notes about this:
1. If the sound is set to autoplay, it won't get disabled on unhide, but at times it seems to change the volume level of the sound, although this could just be my ears playing tricks on me.
2. It does not matter what is called, hide, unhide, toggle, they all turn the sound off if it's previous state was toggled on.
3. It does not ever seem to toggle the sound on if the previous state was off.

The work around for me is just to call a toggle on the sound after the unhide, but I'm sure this won't work for every situation.

We are using UDK-2011-06, Engine version 8623, Changelist 935754. I've been able to reproduce this problem within the template levels.