leavebuster resets

Hi. I have a 20 min cooldown. I wanted to wait it out for a game and i just did it. I waited for like 7 mins, while eating and after coming, i saw that i just waited 7 mins but it showed me that i have 18 mins left...even if i already waited 7 from the 20.If i wait them after waiting the finding game timer doesent work and wont find me a game..