We have a yellow double flowering hibiscus "Edith Parsons." We get lots of buds but they fall before the flower opens. This plant is in full sun, in a pot and the plant looks very healthy. What is preventing the flowers from opening to full bloom?
Infestations can cause early bud drop. Inspect the plant for signs of insects and treat with Neem Oil if you discover this is the problem.
Growing conditions can also cause the plant to drop buds.
Here are some links to help you.