Available quantity is 0 but i own the shares

hello , i am working on a trading strategy which involves trading in pre and post market.
this is my order :

api.submit_order(symbol=sym,
            qty=stock_amnt,side='sell',
            type='limit',limit_price=round(live_close,2),time_in_force='day',extended_hours=True)

this executes correctly , however when i fo api.get_position(symbol) i get this response :

Position({   'asset_class': 'us_equity',
    'asset_id': '63f86a17-0667-45e4-bf6a-cc5646e8f48a',
    'asset_marginable': False,
    'avg_entry_price': '14.5952259164535379',
    'change_today': '-0.0555555555555556',
    'cost_basis': '34240.4',
    'current_price': '14.11',
    'exchange': 'NYSE',
    'lastday_price': '14.94',
    'market_value': '33102.06',
    'qty': '2346',
    'qty_available': '0',
    'side': 'long',
    'symbol': 'STEM',
    'unrealized_intraday_pl': '-1138.3399999999999134',
    'unrealized_intraday_plpc': '-0.0332455228326772',
    'unrealized_pl': '-1138.34',
    'unrealized_plpc': '-0.0332455228326772'})

why is the “qty_avalable” is 0? , i cant close a position because of this as i get this error:

APIError: insufficient qty available for order (requested: 2346, available: 0)

the weird part is that i do actually own the shares and they make/lose me money.

what could be the problem ? is it a bug or just how this type of order works?