If you are not the Falconer Mastery, and are just dipping points into it, you can’t go past the half way point in it’s mastery tree. That’s how masteries work.
You can create a new character the master the Falconry skills, but you would have to do that any way since the issue is that once you have a mastery you can’t change that, and that’s what the Falconer is. So it’s not just specific to the Falconer, it’s any mastery that you want to play that you don’t already have.