Symptoms
SharePoint site Template List is empty during wizard phase.
Diagnoses
When using the SharePoint sites and workplaces event in K2 Studio and doing a Create Site Event, the list of SharePoint site templates are not available and is empty instead.
Resolution
Setting the environment's UI to use Invariant Language (Invariant Country) in IIS fixed the issue.
By default K2 uses Invariant Language (Invariant Country) which targets most languages and should match the one in SharePoint.