Underdark Scout additional attack, does it apply with an Hasted Attack Action?

@LeMarcSharma @JeremyECrawfordUnderdark Scout additional attack on Attack Action, does it apply with an Hasted Attack Action? Seems it can’t. No – it's one attack total with an attack action, not per such action #wotcstaff

— (((Mike Mearls))) (@mikemearls) October 1, 2016