plotting by sc.pl.dpt_timeseries(adata) has no colors

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Hello Scanpy,
I'm using the DPT. Every function works fine except sc.pl.dpt_timeseries(adata). I got no colors of the plot.
Could you please help me with this issue?
Thanks!
Best,
YJ

Minimal code sample (that we can copy&paste without having any data)

adata = sc.datasets.paul15()
adata
sc.pp.log1p(adata)
sc.pp.neighbors(adata, n_neighbors=20, use_rep='X', method='umap')

sc.tl.diffmap(adata)
sc.tl.dpt(adata, n_dcs=10, n_branchings=1)

sc.pl.diffmap(adata, color=['dpt_pseudotime', 'dpt_groups', 'paul15_clusters'])
sc.pl.dpt_groups_pseudotime(adata)
sc.pl.dpt_timeseries(adata, color_map='viridis', show=True)

Versions

Start by running the provided paul15 example through sc.pl.dpt_timeseries(adata, color_map='viridis', show=True) and inspect the dpt_timeseries plotting entry point. Compare its output with the other plotted DPT fields in the sample; done means the timeseries plot displays the expected colors and a regression check covers the reported case.