What lights are you running? High intensity lights make the girls calcium hungry. What does your package recommend? Mine would be 5 ml/gallon at your size (GH). I would also use cal mag on water-only days, assuming you are on a feed/water/feed/water cycle. Monitoring runoff to time flushes doesn’t hurt. 6.2 out is not bad and should not cause any lockouts.
As stated above that plants look pretty good and you are likely just being hyper-observant: one of those ‘helicopter parents’ lol. It’s all good.
If you aren’t following a coco growers’ journal I would strongly suggest you do so.