Unable to set df index in freq 10 min

Question

I am working with a timeseries with Pandas(Python). I am traying to set the index freq to 10min.

I create the new_index:

new_index = pd.date_range("2022-01-01", periods=7844, freq="10 min")

Update my df with the new__index

data_df['new_Date']=new_index

Set date as index

data_df.set_index('new_Date',inplace=True)

Then I print the new index freq:

print(data_df.index.freq)

Output: None

I can't figure out why, even though I explicitly create an index with the freq option, once in the df it is not recognized.