Forbidden Cherry indoor

Your having issues because your pH is off. . The ideal pH for the growing in Coco Coir is between 5.8-6.0 in the Vegetation stage (for high absorption of Nitrogen) and the Flowering stage needs 6.0-6.2 (as its essential for Potassium and Phosphorus intake) pH to sustain proper nutrient levels. Another thing is the plant is probably starving since there is no nutrients in Coco, you need to feed the plant every other day to make sure it's getting the correct nutrients.

So your ph is too low. 5.8 is ideal for coco grows. Coco us heavy irrigation and needs lots of run off. It is to never get dry but never sit in run off. Ph 5.8 on ph 5.8 out in run off. You need to feed at minimum every other day if not every day.