Harrison,
I don't think there is any more annoying, inaccurate, and unreliable piece of equipment than a hygrometer !!!!!
If you ever find one that will not break-the -bank ...let me know

I have 2 ( exo - open probe ) in each tree frog enclosure right this moment that all display different readings despite nice even temps.

In the red eye enclosure ... one says 88% and the other says 58% and they are an inch from each other.

I removed them form the PDF enclosures.

Blow on it ! move it and see what happens ..... Hair pulling ! frustration.