missing Whites tree frog

[DonLisk]

I would put some dishes of de-chlorinated tap water around the house so if it is out it can get to water.

They travel fast and can tour a whole house overnight.
Look for dust bunnies pulled out of unusual places, mine left a trail of them everywhere they traveled.

Now, they are excellent at hiding and may have buried themselves into the tanks substrate, slid down into the leaves of a plant, or found that perfect hiding place. Hopefully tonight he will come out and explore.
Just keep the tank misted and the humidity up and keep your eyes peeled for anything unusual around the floors of the house.