Can't print Spectrum1D object created by default loader for JWST s3d data cube

Spectrum1D.read of JWST s3d file uses default loader rather than JWST s3d loader. A Spectrum1D object loaded this way can't be printed:

---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
in
1 #Try printing Spectrum1D obect
----> 2 print(spec1d_untrimmed)
3 #print(spec1d_untrimmed.spectral_axis)
4 #print(spec1d_untrimmed.uncertainty)

~/miniconda3/envs/jdaviz1.1/lib/python3.9/site-packages/specutils/spectra/spectrum1d.py in __str__(self)
457 for i, flux in enumerate(self.flux):
458 label = 'flux{:2}'.format(i)
--> 459 result += self._format_array_summary(label, flux) + '\n'
460 else:
461 result += self._format_array_summary('flux', self.flux) + '\n'

~/miniconda3/envs/jdaviz1.1/lib/python3.9/site-packages/specutils/spectra/spectrum1d.py in _format_array_summary(self, label, array)
441 mean = np.mean(array)
442 s = "{:17} [ {:.5}, ..., {:.5} ], mean={:.5}"
--> 443 return s.format(label+':', array[0], array[-1], mean)
444 else:
445 return "{:17} [ ], mean= n/a".format(label+':')

~/miniconda3/envs/jdaviz1.1/lib/python3.9/site-packages/astropy/units/quantity.py in __format__(self, format_spec)
1255 """
1256 try:
-> 1257 value = format(self.value, format_spec)
1258 full_format_spec = "s"
1259 except ValueError:

TypeError: unsupported format string passed to numpy.ndarray.__format__

Start in specutils/spectra/spectrum1d.py at __str__ and _format_array_summary, then reproduce the failure with the JWST s3d data cube described in the report. Trace how the default loader shapes the flux array and verify that printing the resulting Spectrum1D completes without the reported TypeError.

Written by the indexing model from the issue text.