I've switched some oncidium, phals, and dendrobium seedlings to s/h several weels ago and nothing except root rot is ocurring.
Are you supposed to keep water in the s/h pots filled to the drainage holes, or do you let all the water evaporate before filling again?
The roots that are rotting are the ones that were on the plant when you put it into s/h I assume and they are not adapted to the environment of s/h. Hopefully the plant is in growth stage and will send new roots down into the medium, these roots will be adapted and hopefully will not rot but rather thrive. It's hard for roots that were grown in another medium and another type of growing to make the adjustment to s/h without rotting...