Workflow stops with custom Provider activity in started state

Problem

You have a service with a process containing a custom provider activity. When ordered, the service order is never completed. In the Order management view in Admin web it can be seen that the workflow has reached the custom activity, this activity is in state started, but the workflow never continues from this step. There is no error in the Event log on the provisioning server.

Solution

Check the return values from the custom provider. For example, Enum types are not supported.