Roto Brush PROBLEM

Try resetting the effect in the Effect Controls panel, there may be a wrong setting. And remember, do not go beyond the limits of the element you want to select. If you want to select a person, select only the inner part of the person's figure, if you select with the brush outside then you will also select the outside.

Have you tried to delete the Rotobrush effect applied to your layer and start again? It looks like you have created a previous brush stroke and it is affecting the current selections.