When the "View Only" license type does not appear in the portlet, then this means that there are no users with a "View Only" License.
To check users and their license follow these steps:
1. Go to the Administration - License Information page.
2. Click into the type of license (Full or Restricted), that list will display users that you believe should be of "View Only" type.
3. Click on the user in question to see the assigned rights.
4. Here you can also see if the rights are of "Restricted" or "Full" type.
5. Go back to the user details under Administration - Resources and open the Resource's Access Rights, and check where these rights are granted.
6. In case you don't want this user to have these restricted/full rights, then remove the rights and the user count will show up under "View Only" in the 'User Count by License Type'' portlet.