`beat caches view` doesn't work

I get the following:

path: e4/fb/dc/b2f4751a65179e51b472c4b8c1efbec86441e61194bc02442971ae3405
  dataformat: tutorial/linear_machine/1
Traceback (most recent call last):
  File "/home/jae/miniconda3/envs/beatedit/bin/beat", line 11, in <module>
    sys.exit(main())
  File "/home/jae/miniconda3/envs/beatedit/lib/python3.6/site-packages/beat/cmdline/scripts/beat.py", line 186, in main
    return module.process(args)
  File "/home/jae/miniconda3/envs/beatedit/lib/python3.6/site-packages/beat/cmdline/cache.py", line 191, in process
    return view(args['config'], args['<path>'], start, end)
  File "/home/jae/miniconda3/envs/beatedit/lib/python3.6/site-packages/beat/cmdline/cache.py", line 164, in view
    cls=NumpyJSONEncoder).\
  File "/home/jae/.local/lib/python3.6/site-packages/simplejson/__init__.py", line 397, in dumps
    **kw).encode(obj)
  File "/home/jae/.local/lib/python3.6/site-packages/simplejson/encoder.py", line 293, in encode
    chunks = list(chunks)
  File "/home/jae/.local/lib/python3.6/site-packages/simplejson/encoder.py", line 677, in _iterencode
    for chunk in _iterencode_dict(o, _current_indent_level):
  File "/home/jae/.local/lib/python3.6/site-packages/simplejson/encoder.py", line 634, in _iterencode_dict
    for chunk in chunks:
  File "/home/jae/.local/lib/python3.6/site-packages/simplejson/encoder.py", line 697, in _iterencode
    o = _default(o)
  File "/home/jae/miniconda3/envs/beatedit/lib/python3.6/site-packages/beat/backend/python/utils.py", line 354, in default
    return simplejson.JSONEncoder.default(self, obj)
  File "/home/jae/.local/lib/python3.6/site-packages/simplejson/encoder.py", line 268, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <map object at 0x7f1b3d54a4e0> is not JSON serializable

This happens with any cache I've tried. Does it work for anyone?