When shares are sold from investments, it reflects under the positions tab as a new negative (short) position, which is normal. This allows you to make intraday trades using the stocks you hold and helps you in monitoring your intraday P&L.
When you sell shares from your holdings, the amount of shares in the investments tab will decrease and this will be shown as a CNC short in the positions tab.
The sale of the share will be seen in your trade book and holdings at the end of the day. These shares will be sold based on the price at which you placed the CNC sell order.
Please remember when you sell shares from your investments, in the investments section, the quantity and invested amount will be shown as ZERO. However, your P&L will keep changing till the end of the trading day according to the selling price and LTP.