mopidy: Sorting in ncmpcpp working very slow and unstable (may be only with Spotify backend)

steps to reproduce: 0) open ncmpcpp

1. add few hundreds songs from spotify to main playlist
2. sort main playlist (Ctrl+S)

Mopidy responds slower and after some time throws the exception:

ERROR    Unhandled exception in MpdFrontend (urn:uuid:9b5696c9-0261-4eea-8132-f43b1017f286):
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/pykka/actor.py", line 200, in _actor_loop
    response = self._handle_receive(message)
  File "/usr/lib/python2.7/site-packages/pykka/actor.py", line 294, in _handle_receive
    return callee(*message['args'], **message['kwargs'])
  File "/usr/lib/python2.7/site-packages/mopidy/mpd/actor.py", line 84, in on_event
    self.send_idle(_CORE_EVENTS_TO_IDLE_SUBSYSTEMS[event])
  File "/usr/lib/python2.7/site-packages/mopidy/mpd/actor.py", line 88, in send_idle
    listener.send(session.MpdSession, subsystem)
  File "/usr/lib/python2.7/site-packages/mopidy/listener.py", line 27, in send
    'kwargs': kwargs,
  File "/usr/lib/python2.7/site-packages/pykka/actor.py", line 437, in tell
    raise _ActorDeadError('%s not found' % self)
ActorDeadError: MpdSession (urn:uuid:4c427b21-ab0b-426d-b795-efb9afb46db0) not found

UPD: forgot to mention what i am using release 2.0.0