The actual hook type most people will generally be looking for is a 135 deg hook, to ensure the stirrups actually look like the one in the image above.
The reaosn you cannot see a 135 deg hook is because the extensions only look for the "Standard Hook" type, and not the Stirrup/Tie Hook or Stirrup/Tie Seismic Hook.
The default template that comes with Revit only gives two options for the Standard hook, 90 deg. or 180 deg.
Create a new hook type.
In the project browser, right click on the Standard hook, and click duplicate. rename the hook to be Standard Hook - 135 deg. In the type properties for the hook change the angle to 135 degrees, making sure the "style" is set to standard. Save the changes and head back to the extensions to try again.
Sure enough, the 135 deg. Hook type is in the drop down list, making life much easier when rienforcing multiple beams of the same type.