Brassocattleya leaf turned brown from the bottom up before falling off

[OrchideeNormus]

I got my Blc. Memoria Vida Lee 'Limelight' (Brassocattleya Binosa x Lc. Brazilian Treaure) on January 17th, it was described as a young plant about 2-3 years from blooming size. I gave it a few days before repotting it into a self watering pot (the kind with a cone that goes down into the water) with LECA. As of now I grow on a windowsill basically because it's too cold outside (this will change during the summer, moving outside) my weather station says the temperature has ranged from 68° to 79° and the humidity has ranged from 20% to 26% in the last 36 hours. I use RO water with a very diluted fertilizer (Jacks classic orchid special 30-10-10, lowest recommendation is 1/4 tsp per gallon and I cut that in half) I did a flush last weekend with plain RO water and then refilled the reservoir with my regular feed and a boost of calmag. I tested the PH and it was about 5.9 initially, tonight it's 7.13 (I expected the rise because of the LECA). Everything has been going very smoothly, the roots have remained green and hydrated and the leaves were all green and firm. Last night I noticed one of the biggest leaves turned a light green. Whatever happened, happened very quickly because tonight I noticed the bottom half of the leaf was a dark brown. When I went to inspect a little closer the leaf fell off the plant. The cane doesn't seem to feel mushy or anything and is still green where the leaf came off. The rest of the leaves are perfectly fine as far as I can tell. This is my first and only type of orchid in the cattleya alliance, I have heard that they sulk after a repotting but this seems a bit extreme lol. I tried to get the best close up picture of the plant that I could, if anyone can see anything that looks like it needs attention or you want a picture of something in specific of the plant, or you just need more information in general please let me know! Im also including a picture of the leaf that fell