Missing Historical Prices

Environment

Language
Python 3.7

Problem

Summary
When I run the code below, August 14th and 13th are missing for some reason. Does anyone know what could be causing this?

Example Code
start_date = pd.Timestamp(“2020-08-11”, tz=“America/New_York”).isoformat()
end_date = pd.Timestamp(“2020-08-17”, tz=“America/New_York”).isoformat()

df = api.get_barset(
“AAPL”,
‘1D’,
limit=None,
start=start_date,
end=end_date,
after=None,
until=None,
).df

df.tail()