NAN values in HW Series

[kwadwobro]

I am wondering why there are nan values in the HW column created on this line of the code

def compute_home_wins(self, matches_df: pd.DataFrame) -> pd.DataFrame:
matches_df['HW'] = self._compute_last_results(matches_df=matches_df, team_column='Home Team', result='H')

    return matches_df

in database/repositories/leagues.py