mne-bids: copyfile_eeglab not working

Description

I am currently attempting to copy EEGLAB files via copyfiles_eeglab with a new (BIDS compliant) name. The files are moved and renamed according to the specifications. However, when trying to open those files with MNE there is an error message:

Traceback (most recent call last):

  File "<ipython-input-17-8c31a528db9f>", line 1, in <module>
    raw_bids = mne.io.read_raw_eeglab('sub-001_ses-D1_task-RS2_run-02_eeg.set')

  File "C:\Users\Nils Rosjat\Anaconda3\lib\site-packages\mne\io\eeglab\eeglab.py", line 222, in read_raw_eeglab
    eog=eog, verbose=verbose, uint16_codec=uint16_codec)

  File "<decorator-gen-216>", line 24, in __init__

  File "C:\Users\Nils Rosjat\Anaconda3\lib\site-packages\mne\io\eeglab\eeglab.py", line 326, in __init__
    info, eeg_montage, update_ch_names = _get_info(eeg, eog=eog)

  File "C:\Users\Nils Rosjat\Anaconda3\lib\site-packages\mne\io\eeglab\eeglab.py", line 145, in _get_info
    ch_names, eeg_montage = _get_eeg_montage_information(eeg, has_pos)

  File "C:\Users\Nils Rosjat\Anaconda3\lib\site-packages\mne\io\eeglab\eeglab.py", line 123, in _get_eeg_montage_information
    ch_pos=dict(zip(ch_names, np.array(pos))),

TypeError: unhashable type: 'numpy.ndarray'

When comparing the original MATLAB structure:

with the newly created structure:

I saw that several entries were replaced by numpy array objects. This seems to happen already in

https://github.com/mne-tools/mne-bids/blob/3d96c5b2af004b57085b5c9bf884e18279707a3c/mne_bids/copyfiles.py#L531-L532

When replacing loadmat with read_mat (from mne.externals.pymatreader) this seems to work better, but still after saving the dict with savemat the same issue remains.

Script used for conversion

mne_bids version: 0.5

import os.path as op
import os

import mne

from mne_bids import BIDSPath
from mne_bids.copyfiles import copyfile_eeglab

parent_dir = op.abspath('..')
data_path = op.join(parent_dir,'data')

sub_dirs = ['001']
sessions = ['D1']
tasks = ['Tap']

for sub_dir in sub_dirs:
    for session in sessions:
        for task in tasks:
                sub_path = op.join(data_path, sub_dir, 'ses-' + session)
                sub_id = os.listdir(sub_path)[0].split('_')[0]
                set_name = sub_id + '_' + session + '_' + task + '_Nils_IntRef_CSD.set'
                set_file = op.join(data_path, sub_dir, 'ses-' + session,set_name)
                set_rename = 'sub-' + sub_dir + '_ses-' + session + '_task-' + task + '_desc-CSD.set'
                set_file_renamed = op.join(data_path, 'sub-' + sub_dir, 'ses-' + session, 'eeg', set_rename)
                copyfile_eeglab(set_file, set_file_renamed)