Why does "iex" and "sip" feed not show all minutes?

Alpaca Market Data
1

I am currently new to Alpaca and am trying to use my paper account with the iex exchange to get historical data from Apple stocks. I have a bit of an issue though. When I create a StockBarsRequest class with the datetime set to start at 0:00 and end at 23:59, it only shows me a portion from within that timeframe. However, I am able to get most of the data using sip, but the data sometimes skips a few minutes. For example, if I set my dates to START_TIME = datetime(2024, 1, 25, 9, 30) and END_TIME = datetime(2024, 1, 25, 16, 0), it only shows the minutes starting from 2024-01-25 13:09:00+00:00 to 2024-01-25 20:59:00+00:00 in my dataframe. Is the timezone or something different? I am having a hard time understanding why this is. Here is my current code using ‘iex’.

START_TIME = datetime(2024, 1, 25, 9, 30)
END_TIME = datetime(2024, 1, 25, 16, 0)

stock_client = StockHistoricalDataClient(
                         api_key=API_KEY,
                         secret_key=SECRET_KEY
                         )

req_aapl = StockBarsRequest(
                         symbol_or_symbols=["AAPL"],
                         start=START_TIME,
                         end=END_TIME,
                         timeframe=TimeFrame.Minute,
                         feed="iex" # I believe this is the free real-time market feed,
                         )

aapl_bars = stock_client.get_stock_bars(req_aapl)

# adds the timestamp column for the dataframe
aapl_df = aapl_bars.df
aapl_df['timestamp'] = aapl_df.index
aapl_df['timestamp'] = [x[1] if isinstance(x, tuple) and len(x) == 2 else x for x in aapl_df['timestamp']]
aapl_df.reset_index(drop=True, inplace=True)

# outputs to a .csv file
output_aapl = os.path.join(OUTPUT_DIR, 'aapl_data.csv')
aapl_df.to_csv(output_aapl, index=False)

If somebody could help me out on why my dataframe does not seem to show times before 1PM that would be great!