'MeasurementControl' has no '_thread_data' attribute

I'm not sure how to reproduce this error. I don't get it every time and it seems a bit random. I get it sometimes when running the MC.run_adaptive function in order to do mixer calibration.

The flow is fairly common though: instanciate measurementcontrol (with instrument monitor and plot monitor), attach settables and gettable, where the gettable is:

power = Gettable(qcodes.Parameter(name='power', label='Power', unit='dBm', get_cmd=self.sh.power))

Where self.sh.power gets the signalhound power readout via its driver.

The error traceback is:

AttributeError: 'MeasurementControl' object and its delegates have no attribute '_thread_data'
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<timed exec> in <module>

g:\My Drive\Code\amazon-demonstrations\calibration_utilities.py in minimize_unwanted_sideband(self, ref_lvl, options)
    227         self.mc.settables(settables)
    228 
--> 229         dset = self.mc.run_adaptive('minimize_sideband', af_pars)
    230 
    231         #Get datasets

g:\my drive\code\quantify-core\quantify_core\measurement\control.py in run_adaptive(self, name, params)
    321                 adaptive_function(measure, **af_pars_copy)
    322 
--> 323         self._reset()
    324         self.setpoints(
    325             np.empty((64, len(self._settable_pars)))

g:\my drive\code\quantify-core\quantify_core\measurement\control.py in _reset(self)
    175         self._batch_size_last = None
    176         # Reset KeyboardInterrupt counter
--> 177         self._thread_data.events_num = 0
    178         # Assign handler to interrupt signal
    179         signal.signal(signal.SIGINT, self._interrupt_handler)

~\Anaconda3\envs\quantify\lib\site-packages\qcodes\utils\helpers.py in __getattr__(self, key)
    434         raise AttributeError(
    435             "'{}' object and its delegates have no attribute '{}'".format(
--> 436                 self.__class__.__name__, key))
    437 
    438     def __dir__(self) -> List[str]:

AttributeError: 'MeasurementControl' object and its delegates have no attribute '_thread_data'

If I recall correctly, when this error happens, it keeps appearing and I had to reset the notebook to make it go away.