Whether an asset produces income or not is irrelevant for capital gains tax.
Capital gains tax is a tax on gains booked to the capital account and has nothing to do with income tax, except that it is collected using the income tax system. It is a totally different type of thing. A collection of stamps or coins does not produce income (as explain here before it is a fruitless tree) but its disposal at a profit does incur CGT.
Capital is the tree and income the fruits. The fact that a tree can grow it does not change its nature as tree.
