Would this be not knowing how to do something?
After each go home, Bob makes a few attempts of what the instructor tried to teach him. While doing it, he does not have a good feeling about it, is not sure if it would be what she would have been looking for, or this is [how you do] it.
Then, Bob finds a video of how to do it after research.
Would this be not knowing how to do it, focusing on the part when I said *Each time Bob tries to do it the way that resulted in her praising him, she considered him to be losing control/confidence*?