*SOLVED You must to cast Process to either a DesignerProcess, DockerProcess or YamlProcess. Repo updated.
There is an issue in the .NET Client libraries for the Azure DevOps REST API.
When attempting to iterate over the Build tasks within a build definition there are no accessible properties beneath Process.
For similar past bug reports see;
- https://developercommunity.visualstudio.com/content/problem/195362/getfulldefinitionsasync0-does-not-populate-the-bui.html
- https://dev.azure.com/mseng/AzureDevOps/_workitems/edit/1180374/
- https://stackoverflow.com/questions/52205058/retrieve-the-list-of-tasks-for-build-definition-using-net-client-libraries-for
Currently the only way to get this to work in .NET is to use dynamic, however this isn't desireable as we lose strong typing!