Yellow spots on vanda leaves

[Mercurianmad]

Hi guys. I’ve potted up my Vandas in lava rock inside baskets with a coconut fiber nest around them. They dry out in two-three days. So why are there yellow spots on my orchid leaves? There is also a sticky spot in the base of the stem. When I got sticky spots on my phalaenopsis it was because of too much humidity. But since these dry out quickly I’m wondering what the problem is. There obviously is one and I’d like to resolve it for them.

I dug up their roots. They are not growing new roots but their roots are not squishy or rotting either. They look nicely moist because I watered them this morning. And I don’t water them until the roots are bone dry. I have a humidifier on them now but they’ve been without a humidifier for three days - the rh has been about 57 without the humidifier, on humidity trays. Ideas? Thank you.