Gamelift is always active. How do I make it inactive?

I manually turned on my Gamelift fleet on in order to test it out but now I want it to be inactive. In the past, I've typically just manually set the instance counts to 0 and the fleet would become inactive after about 10 minutes. For whatever reason, this is no longer the case. Does anyone know how I can do this without deleting my fleet? Again, I've already managed this in the past but it stopped working yesterday.