If you haven't had any NI plugins before, perhaps they've been put into Program files/Steinberg/VST plugins.
Many VST get installed there by default unless you change where they go manually during installation. Or you could look in Program files x86.
A way to find out for sure is to start the installation again and look where the files were put by default then cancel the installation. Go to that folder and check your plugins are there then point Sonar to scan that folder.
Or have you in fact rescanned VSTs since you installed Ultimate.