Why does one of my lady Master Researchers have a full bar unlike the other female and 2 Males,all of them are rated "Master".

She has inproved as much as she can in the field . the others are masters but they still have a little more room to grow.

How do I help them get their max??

just have them keep doing what their doing. or keep their box checked (the one next to their master skill) and they will go off and practice their skill on their own