pl.violin will not take "hue" kwarg for seaborn?

Trying to make a violin plot adding the seaborn hue argument will result in ValueError.
In adata, 'timepoint' and 'replicate' are categorical adata.obs containing floats and ints, respectively. 'timepoint' is the age of the embryo from which cells were isolated (9.5, 10.5, etc) and 'replicate' the number of the replica (1, 2, 3).

sc.pl.violin(adata, 'n_genes', jitter=0.4, groupby = 'timepoint', stripplot=False, hue='replicate')

sc.pl.violin(adata, 'n_genes', jitter=0.4, groupby = 'timepoint', stripplot=False, hue='replicate')
Traceback (most recent call last):

  File "<ipython-input-5-756b321177a2>", line 1, in <module>
    sc.pl.violin(adata, 'n_genes', jitter=0.4, groupby = 'timepoint', stripplot=False, hue='replicate')

  File "/home/auesro/anaconda3/envs/Scanpy/lib/python3.7/site-packages/scanpy/plotting/_anndata.py", line 759, in violin
    **kwds,

  File "/home/auesro/anaconda3/envs/Scanpy/lib/python3.7/site-packages/seaborn/categorical.py", line 2393, in violinplot
    color, palette, saturation)

  File "/home/auesro/anaconda3/envs/Scanpy/lib/python3.7/site-packages/seaborn/categorical.py", line 559, in __init__
    self.establish_variables(x, y, hue, data, orient, order, hue_order)

  File "/home/auesro/anaconda3/envs/Scanpy/lib/python3.7/site-packages/seaborn/categorical.py", line 152, in establish_variables
    raise ValueError(err)

ValueError: Could not interpret input 'replicate'

Versions:

scanpy==1.4.6 anndata==0.7.1 umap==0.4.1 numpy==1.18.1 scipy==1.4.1 pandas==1.0.3 scikit-learn==0.22.2.post1 statsmodels==0.11.1 python-igraph==0.8.0

Start at the sc.pl.violin entry point and reproduce the reported call with the supplied categorical timepoint and replicate fields. Trace how the hue argument is passed to seaborn and verify the behavior against the reported versions. Done means the example accepts hue without raising the ValueError.