Virtual Sound Decoder + LocoNet hardware. If the user assigns an address to a VSDecoder first, and then tries to assign that address to a LocoNet-based throttle, the LocoNet throttle must "steal" the address away from the VSDecoder even though the VSDecoder is listen-only.
Apparent root-cause: LocoNetThrottleManager.addListener() creates a throttle if one is not already existing for the given address. This results in the LocoNetSlot being marked "In Use" even though it doesn't need to be.
Resolution is not clear at this time.