PyQtGraph multiprocessing 'ClosedError'

I get this error sometimes while running a Rabi calibration. I'm not sure what triggers it, as it only happens sometimes, and apparently randomly.

This is the code I run:

from qcodes.instrument.parameter import ManualParameter
from quantify_scheduler.gettables import ScheduleVectorAcqGettable
import numpy as np

amp = ManualParameter(name='amplitude', unit='V', label='Amplitude')

rabi_sched_kwargs = {
    'pulse_amp': amp,  # When we specify an argument as a parameter, the current value is evaluated every iteration.
                       # We use this so that we can sweep it and a new schedule is generated and compiled.
    'pulse_duration': transmon.mw_pulse_duration(),
    'frequency': transmon.freq_01(),
    'qubit': 'q0'
    }

gettable = ScheduleVectorAcqGettable(None, 
                                     schedule_function=rabi_sched, 
                                     schedule_kwargs=rabi_sched_kwargs, 
                                     device_cfg=transmon.generate_device_config(), 
                                     hardware_cfg=hw_config, 
                                     instr_coord=IC, 
                                     hardware_averages=1000
                                    )




amplitude_setpoints = np.linspace(0, 0.25, 12)

MC.settables(amp)
MC.setpoints(amplitude_setpoints)
MC.gettables(gettable)

dset = MC.run('Rabi')

And this is the result I get:

ClosedError
---------------------------------------------------------------------------
ClosedError                               Traceback (most recent call last)
<ipython-input-29-d713ae80c1da> in <module>
      7 MC.gettables(gettable)
      8 
----> 9 dset = MC.run('Rabi')

g:\my drive\code\quantify-core\quantify_core\measurement\control.py in run(self, name, soft_avg)
    242                 if self.verbose():
    243                     print("Starting iterative measurement...")
--> 244                 self._run_iterative()
    245         except KeyboardInterrupt:
    246             print("\nInterrupt signaled, exiting gracefully...")

g:\my drive\code\quantify-core\quantify_core\measurement\control.py in _run_iterative(self)
    346                 self._iterative_set_and_get(row, self._curr_setpoint_idx())
    347                 self._nr_acquired_values += 1
--> 348                 self._update()
    349                 self._check_interrupt()
    350             self._loop_count += 1

g:\my drive\code\quantify-core\quantify_core\measurement\control.py in _update(self, print_message)
    507 
    508             if self.instrument_monitor():
--> 509                 self.instrument_monitor.get_instr().update()
    510 
    511             self._last_upd = time.time()

g:\my drive\code\quantify-core\quantify_core\visualization\instrument_monitor.py in update(self)
     97             snap = snapshot(update=False, clean=True)
     98             try:
---> 99                 self.widget.setData(snap["instruments"])
    100             except AttributeError as e:
    101                 # This is to catch any potential pickling problems with the snapshot.

~\Anaconda3\envs\quantify\lib\site-packages\pyqtgraph\multiprocess\remoteproxy.py in __getattr__(self, attr, **k    900         else:
    901             #opts = self._getProxyOptions()
--> 902             return self._handler.getObjAttr(self, attr, **opts)
    903 
    904     def _deferredAttr(self, attr):

~\Anaconda3\envs\quantify\lib\site-packages\pyqtgraph\multiprocess\remoteproxy.py in getObjAttr(self, obj, attr, **kwds)
    531 
    532     def getObjAttr(self, obj, attr, **kwds):
--> 533         return self.send(request='getObjAttr', opts=dict(obj=obj, attr=attr), **kwds)
    534 
    535     def getObjValue(self, obj, **kwds):

~\Anaconda3\envs\quantify\lib\site-packages\pyqtgraph\multiprocess\remoteproxy.py in send(self, request, opts, reqId, callSync, timeout, returnType, byteData, **kwds)
    415         if self.exited:
    416             self.debugMsg('  send: exited already; raise ClosedError.')
--> 417             raise ClosedError()
    418 
    419         with self.sendLock:

ClosedError: