Can't level McGinnis' third skill while it is active

[Acidm8]

While McGinnis' third skill is active and the icon has changed to the "remove wall" button, you are unable to level up the skill.

Steps to reproduce:

1. Cast McGinnis' third ability (Spectral Wall) while you have a skill point to spend
2. Press TAB to open the skills menu
3. Click on the third ability to level it up

I would expect the above steps to level up the ability, with any additional bonuses applying to the next time the ability is used, instead nothing happens and McGinnis' uses her primary shooting attack, implying that the game is registering a normal left click input.