My nodding violet is not flowering. It is a healthy looking plant

It could due to too much Nitrogen-based fertiliser, but not enough Potassium. Try weekly application of 'Yates Thrive Roses & Flowers Natural Fish & Seaweed+ Concentrate' as a complete fertiliser to assist with healthy growth and prolific, beautiful flowers. Click here for more info on this product: https://www.yates.com.au/product/garden-fertilisers/organic-based/yates-thrive-natural-roses-flowers-concentrate