Miltoniopsis Leaves Yellowing After Repot

[scy]

I noticed new growth coming from my miltoniopsis and decided now would be the best time to repot, since it was tightly packed in an unknown medium. (I received it as a gift for Christmas.) When I took it out of its pot, I saw that the previous medium was small bark chips and sphag. The medium JUST started to decompose and the roots were beautiful and in great shape!

I soaked small bark chips in water overnight and then sprayed with rubbing alcohol to kill off any bacteria before potting it up. I teased it around the roots and gently tapped it down to make sure it was firmly potted. I watered it with the recommended dilution of KLN solution (1/4 tsp per liter of water). Using a wooden skewer to help me determine when the medium has dried out, it was bone dry half a week later. I rewatered using the same solution and now I noticed that 2 of the outer leaves have turned yellow.

Is potting medium of only small bark chips sufficient or should I add some PrimeAgra in the mix as well? Is this due to the KLN solution or something else I did? I plan on just flushing it out and watering with regular water on future waterings. Is there anything else I can do to help it now? Thanks in advance for the advice!