FlyerTalk Evangelist
Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: BA Silver, TK E+, AA PP, Hyatt Globalist, Marriott LT Plat, Hilton Diamond
Posts: 13,041
Who advised you that it wouldn't count? Do you believe whoever it was?
In my experience a day use stay works exactly the same as a standard overnight stay EXCEPT when something goes wrong with its posting to your account and Hilton's lazy customer service team decides to invent an excuse rather than solve the problem.