Here is a relevant Pega documentation - Adding a traditional Case Type to a Constellation application. It worked fine when I tried the steps. If the issue still persists aftet following all the steps, I would raise a support ticket with Pega.
If you want to try launching a Contellation case type in a UI-Kit application, this article has the steps to configure - How to launch a Constellation case from a UI-Kit case and exchange data - though the previous pattern should be the recommended model using Constellation application as primary.