When you enter the HEARTS LANDMARK, you'll see a column of daily gifts on the left-hand side that run on timers in a subsequent order.

Since the timers for daily gifts run in a subsequent order, once you collect your CAPITAL, the timer will start counting down for ELBOW GREASE. Once you collect your ELBOW GREASE, the timer will start counting down for HEARTS. Then you’ll be able to collect those HEARTS!

Also, reward timers have been reduced from 4 hours to 2 hours in a recent update which means you can collect your daily hearts sooner!