While we get the dataframe from eikon api for Daily volumes, on the days where trading doesn't happen is filled with 0 instead of just returning blanks.
get_data has a NULL parameter (NA|ZERO|BLANK), however, it does not seem to work for time series over get_data() call. So, the only two things I can suggest is either to use get_timeseries() or use pandas:
df.replace(0, np.nan, inplace=True)
