This is normal. Unlike past Studio versions, the Instant DVD Recorder software is installed independently of the Studio software. During the installation process, the following screen is presented. To install Instant DVD Recorder, click the Instant DVD Recorder button outlined in red.
If Studio 12 has already been installed and you have since closed the installer, start the installation process again, this time only select the Instant DVD Recorder application and follow any on-screen prompts.