Whenever you import a manual investment to a pie, the ‘Sell’ button will disappear from its tab.
The share will remain available in your ‘Investments’ tab, but you will no longer be able to sell it from there. To sell the specific stock, you will have to use the pie's Withdraw option.
Alternatively, you can use the Export Investments option in the More Actions tab at the bottom of your Pie. 👇