Awakened added lightning damage level 10 bug

The tooltip on level 10 awakened added lightning damage (possibly also the other added X damage) says that it adds +2 levels of supported lightning skill gems, but does not seem to add 2 levels.

I can confirm the same for Awakened Added Chaos Damage. I've compared it to Awakened Added Chaos Damage lvl 9 and even on my skill DPS thumbnail it seems like only the added damage from higher level support gem is being calculated, not the +1 level.