Certified GKH Gardening Expert
My bet would be placed on soil pH. They require a very alkaline soil to flourish. Most soil sits around 7.0 or a little above or below. These will require that pH be around 9.
This article will help you to care for the Copperleaf: https://www.gardeningknowhow.com/ornamental/shrubs/acalypha/growing-acalypha-copper-plants.htm