Don Salvatore glass top with external mounted hygrometer.

Hello all and thanks in advance for helping me with this issue. I have recently purchased this humidor and noticed the hygrometer wasn't keeping the correct reading when it was mounted on the front of the box. I looked in the box, and the hole that was made in the box was no where near the vents for the hygrometer to sense humidity. I carefully cleared away the wood blocking the vents but the reading stayed the same. I then took the hygrometer out, blocked the opening, and put it in the humidor along with another digital hygrometer. After a few hours both hygrometers had the same humidity reading. Am I doing something wrong when the hygrometer is mounted on the front of the humidor? Once again thanks for your suggestions.
Here are a few pictures so you can understand the situation. The numbers displayed are not actual because I have been doing other experiments which have fluctuated the read outs on the hygrometers. 20181228_130150.jpg 20181228_130724.jpg 20181228_125150.jpg