"Ray @ First Rays Orchids" writes:
If your epi's developed the correct kind of roots but are now rotting, it is
likely due to insufficient warmth.

Then that is probably the problem. I will try punching a hole or two
extra in the sides of the pots for a bit more air circulation, and
placing them in a slightly warmer location. They are close to a cold
concrete wall right now.

Geir