arlpy: failed to calculate eigen rays with newer version of arlpy (ubuntu 20.04)

Newer version is failed to calculate ray tracing.

Here is the output of my pip freeze - pip_freeze.txt

Here is the error while computing eigen rays. I had also attached copy of example notebook for reference.

bellhop-Copy1.pdf

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-25-1af3b30f110e> in <module>
----> 1 rays = pm.compute_eigenrays(env)
      2 pm.plot_rays(rays, env=env, width=900)

~/.local/lib/python3.8/site-packages/arlpy/uwapm.py in compute_eigenrays(env, tx_depth_ndx, rx_depth_ndx, rx_range_ndx, model, debug)
    352     if debug:
    353         print('[DEBUG] Model: '+model_name)
--> 354     return model.run(env, eigenrays, debug)
    355 
    356 def compute_rays(env, tx_depth_ndx=0, model=None, debug=False):

~/.local/lib/python3.8/site-packages/arlpy/uwapm.py in run(self, env, task, debug)
    605             else:
    606                 try:
--> 607                     results = taskmap[task][1](fname_base)
    608                 except FileNotFoundError:
    609                     print('[WARN] Bellhop did not generate expected output file')

~/.local/lib/python3.8/site-packages/arlpy/uwapm.py in _load_rays(self, fname_base)
    819                     'ray': [ray]
    820                 }))
--> 821         return _pd.concat(rays)
    822 
    823     def _load_shd(self, fname_base):

~/.local/lib/python3.8/site-packages/pandas/core/reshape/concat.py in concat(objs, axis, join, ignore_index, keys, levels, names, verify_integrity, sort, copy)
    269     ValueError: Indexes have overlapping values: ['a']
    270     """
--> 271     op = _Concatenator(
    272         objs,
    273         axis=axis,

~/.local/lib/python3.8/site-packages/pandas/core/reshape/concat.py in __init__(self, objs, axis, join, keys, levels, names, ignore_index, verify_integrity, copy, sort)
    327 
    328         if len(objs) == 0:
--> 329             raise ValueError("No objects to concatenate")
    330 
    331         if keys is None:

ValueError: No objects to concatenate