Final Cut Pro X Folder Limit

I'm currently working using Final Cut Pro X. In trying to create a filing system that fit my needs I noticed that I was unable to create new folders in my Project Library by right-clicking after I hit a limit (19 I think it was). I can still use the keyboard shortcut of "CMD+Shift+N" and it seems to create as many as I need. Is there a reason for the lack of mouse ability once it hits a certain point? Or is it simply a glitch in the programming?