At 3rd level, when a two-handed fighter makes a single attack (with the attack action or a charge) with a two-handed weapon, he adds double his Strength bonus on damage rolls.
When you use the attack action, you can make one attack at your highest base attack bonus that deals additional damage.
What am I missing here? I’m playing Varnhold’s Lot, and my MC’s damage bonus is at +22 (x1,5 Str is accounted for). With his Str score being at 26 (+8), his damage bonus with Overhand Chop should be at +26, which is only attainable via Spring Attack or a basic single attack. Why doesn’t it work with Vital Strike since both require a single attack to be made? Without this, Vital Strike is nigh useless. It becomes almost obsolete after lvl 7 anyway but it seems like you can’t get much bang for your buck even before that, either.
I didn’t bother to make screenshots, sorry. I did report it via the in-game tool, though.