Getting error message when trying to get at risk numbers below KM-plot (lifelines) - pandas

Question

I've used lifelines a lot, but when I'm re-running old code that previously worked fine I get the following error: KeyError: "None of [Index(['At risk', 'Censored', 'Events'], dtype='object')] are in the [index]"
I'm guessing there has been some changes to the code when displaying at risk counts, but I can't find any evidence of it in the lifelines documentation. I am using version 27.0
Snippet of the table with data
index
t2p
O
1
354
False
2
113
False
3
1222
False
4
13
True
5
59
False
6
572
False
Code:
ax = plt.subplot(111)
m = KaplanMeierFitter()
ax = m.fit(h.t2p, h.O, label='PPI').plot_cumulative_density(ax=ax,ci_show=False)
add_at_risk_counts(m)
Full error:
KeyError Traceback (most recent call last)
<ipython-input-96-a8ce3ea9e60c> in <module>
4 ax = m.fit(h.t2p, h.O, label='PPI').plot_cumulative_density(ax=ax,ci_show=False)
5
----> 6 add_at_risk_counts(m)
7
8
~\AppData\Local\Continuum\anaconda3\lib\site-packages\lifelines\plotting.py in add_at_risk_counts(labels, rows_to_show, ypos, xticks, ax, at_risk_count_from_start_of_period, *fitters, **kwargs)
510 .rename({"at_risk": "At risk", "censored": "Censored", "observed": "Events"})
511 )
--> 512 counts.extend([int(c) for c in event_table_slice.loc[rows_to_show]])
513
514 if n_rows > 1:
~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\core\indexing.py in __getitem__(self, key)
1766
1767 maybe_callable = com.apply_if_callable(key, self.obj)
-> 1768 return self._getitem_axis(maybe_callable, axis=axis)
1769
1770 def _is_scalar_access(self, key: Tuple):
~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\core\indexing.py in _getitem_axis(self, key, axis)
1952 raise ValueError("Cannot index with multidimensional key")
1953
-> 1954 return self._getitem_iterable(key, axis=axis)
1955
1956 # nested tuple slicing
~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\core\indexing.py in _getitem_iterable(self, key, axis)
1593 else:
1594 # A collection of keys
-> 1595 keyarr, indexer = self._get_listlike_indexer(key, axis, raise_missing=False)
1596 return self.obj._reindex_with_indexers(
1597 {axis: [keyarr, indexer]}, copy=True, allow_dups=True
~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\core\indexing.py in _get_listlike_indexer(self, key, axis, raise_missing)
1551
1552 self._validate_read_indexer(
-> 1553 keyarr, indexer, o._get_axis_number(axis), raise_missing=raise_missing
1554 )
1555 return keyarr, indexer
~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\core\indexing.py in _validate_read_indexer(self, key, indexer, axis, raise_missing)
1638 if missing == len(indexer):
1639 axis_name = self.obj._get_axis_name(axis)
-> 1640 raise KeyError(f"None of [{key}] are in the [{axis_name}]")
1641
1642 # We (temporarily) allow for some missing keys with .loc, except in
KeyError: "None of [Index(['At risk', 'Censored', 'Events'], dtype='object')] are in the [index]"