Humidity 99% but no condensation?

I’m setting up a quarantine tub for a true red-tailed boa and was having humidity troubles.
I have cypress mulch which I dried outside, no misting in the tub (a 32q Sterilite with 10 total pencil sized ventilation holes) and my humidity is at 99%. I live in Utah, a desert averaging 30% humidity in the summer.

I see no condensation inside the tub, so I am worried my Zoo-Med Digital Thermometer & Hygrometer is a dud. Is it possible this is my actual humidity or do I need a new hygrometer?

I have a few of them, 99 can mean it’s burned out or was fully submerged at somepoint. I had one that always read low on the hygrometer and now it just reads a constant 10. Is the moisture near the heat? What’s the temp in the room? Ac running? Surface temp of the damp substrate?

The room is 76* F.
A/C is on, but no fan running
Ambient temp of 80F with a hot spot of 92F surface temp.
There is no visible moisture, but the Forest Floor feels a little moist, not damp though.
Did that help?