Oncidiums can be picky about being re-potted and may it take a little while to settle into its new medium. I would not be too concerned. The wrinkled pbulb is supporting the newer growth right now. Hopefully the Kelpmax application will encourage new roots soon.
As a general rule, oncidiums with thin roots require more water than those with fat fleshy roots. They key is to learn when the medium is almost dry befor watering again.