Using the 'Bulk edit' option to "Unlink all recurring" works, but the transactions don't fully display as unlinked until page refresh.

Immediately after the bulk action, the teal color and icon disappear, but the recurring item data (i.e. category) still displays in the table. Also, if you open the 'Transaction Details' panel, you will still see the 'Edit recurring item' button.

Once you refresh the page, the transaction data is then displayed correctly, and the button in the 'Transaction Details' panel then displays "Convert to recurring item".