I have two endgame venos one sage and one demon. Both have all skills learned and Have both ascended fox forms, however when I open the dialog with the skill trainer it will still show the foxform skill lit up as one to learn. This also happens on both of my barbs with true form. As long as you have the skills showing as learned in you skill list and are able to use them you are fine, just a glitch no worries. hope this puts your mind at ease :3