You have to add the ST Harmony Activity to the Harmony Activity in the Harmony App.
Seriously, in the Harmony App, go to add devices then select SmartThings. From there, an authorization screen will load up and then click the “Switches” (Harmony Activities that show up in ST) to authorize Harmony to use. Then add the additional step of turning on/off these Switches (ST-Harmony Activities) at the end of the Harmony Activity in the Harmony App. This will give you instant updates in SmartThings where the 5 minute delay is now only a second.
Hope that helps.