The language database has a limited (but unknown) capacity, when you have too many teams some team names are not loaded. You can remove all the long names (using the Tools menu Remove All Long Team Names) and save space for more teams.

As a drawback you will not see the names during friendly matches or other situations of your career because they use the long name. So a good choice is to remove all the long names and then enable the long names of teams important for your career (for example the teams of your Country) checking the Save Full Name Box in the team generic page.