mamba: Exception with mamba update --all

# >>>>>>>>>>>>>>>>>>>>>> ERROR REPORT <<<<<<<<<<<<<<<<<<<<<<

    Traceback (most recent call last):
      File "C:\Miniconda3\lib\site-packages\conda\exceptions.py", line 1079, in __call__
        return func(*args, **kwargs)
      File "C:\Miniconda3\lib\site-packages\mamba\mamba.py", line 872, in exception_converter
        raise e
      File "C:\Miniconda3\lib\site-packages\mamba\mamba.py", line 866, in exception_converter
        exit_code = _wrapped_main(*args, **kwargs)
      File "C:\Miniconda3\lib\site-packages\mamba\mamba.py", line 832, in _wrapped_main
        exit_code = do_call(args, p)
      File "C:\Miniconda3\lib\site-packages\mamba\mamba.py", line 732, in do_call
        exit_code = update(args, parser)
      File "C:\Miniconda3\lib\site-packages\mamba\mamba.py", line 659, in update
        install(args, parser, 'update')
      File "C:\Miniconda3\lib\site-packages\mamba\mamba.py", line 501, in install
        specs.append(pins[key])
    TypeError: tuple indices must be integers or slices, not str

`$ C:\Miniconda3\Scripts\mamba update --all`

platform = win-64
python   = 3.7.7
mamba    = 0.3.2
conda    = 4.8.3