Makes me wonder the same thing if the device was working or not.I was kind of wondering if the device used to measure the humidity was working correctly. Do you get condensation on the glass, if you have moss in the viv is it moist to the touch
I use clear packing tape to stretch across the outside of the screen top of the exo terra and zoo med tanks. The frogs can't get to it, its clear, and cheap.
I usually do a good misting once per day and look at the frogs behaviors. If they are out and about, humidity is usually good. Hiding or soaking, humidity is too low.
Condensation on the glass and droplets on plants are also a good indicator.
These are just some tips for the meantime.