While Logic App SOAP Custom Connector works as-is and with minimal configuration by the user for some services, there are cases where your runtime calls from Logic App to the SOAP Service via the middle tier of API Management won't succeed. Logic App does its best configuring outbound policies that will automatically translate the SOAP server faults back to a REST Json error response. It will sometimes not be sufficient to figure out what's wrong. For these advance scenarios as you can't access the middle tier, multi-tenant instance of API Management directly, you need to reproduce the issue with a dedicated instance of API Management to be able to trace the calls with API Inspector.
Here are some links to get you started:
- API Management basics: https://docs.microsoft.com/en-us/azure/api-management/api-management-key-concepts
- API Management SOAP to REST: https://blogs.msdn.microsoft.com/apimanagement/2016/12/14/soap-to-rest/
- API Inspector: http://aka.ms/apiminspector