Hey everyone, I’m sorry to hear that you’re having trouble with your Scent items. Our team has already been made aware of the issue and they’re working on a solution. The good news is that this issue appears to be just a visual one (for example, in the screenshots that @Australovenator posted the timer has vanished but dinosaurs still have the visual effect on the ground which indicates that they have appeared due to a Scent being used), but the bad news is that you might need to restart your device after each drone session in order to get the dinosaurs to re-appear.
We have noticed that this issue happens most often when a player has moved quickly from one screen to another, such as from Battle to the Map. We recommend waiting for the map to fully load before using a Scent.
In the meantime, if you have experienced this issue and were not able to see or catch any dinosaurs (other than perhaps the first), reach out to our support team at firstname.lastname@example.org in order to give us the opportunity to make this up to you and investigate this further. Thanks!