Need a feature to transfer between your accounts ISA to General and vice versa. It solves the hassle of withdrawing the money manually and adding to your accounts or asking the customer service to move the funds.
This helps to sell and buy the same stock on different accounts without risking the currently traded price. It comes really useful during the start of the new fiscal year to fill your new available ISA pots immediately by selling your general investment account.
This feature is already available in some of the other trading platforms like Trading 212.
Hope this gets added to your prioritised list.