Plant moisture meters aren't really well-suited for orchid culture. They are actually electrical conductivity meters, and rely on a continuous moist path between electrodes to make a measurement. In soil, that's fine, but in chunky media like those we use for orchids, they are of little value.
Orchids do the majority of their gas exchange through the root system, rather than leaves like terrestrial plants, so "overwatering" an orchid is more accurately described as "suffocating the roots". If your soil moisture meter is giving you a high reading, that's probably exactly what's happening.