Help in identifying Burnt tips amnesia haze

Looks like two issues to me. The brown tips are a sign of overfeeding while the yellow edges are indicating a second issue of imbalance. Are you measuring the TDS of the runoff? It should be less than going in otherwise it's too much. I'd guess a deficiency of something. Are you keeping a log to keep track of what you have given the plant? Yellow spots are like having a fever, you know something is wrong but no what yet. The measurements should help narrow this down as well as reading more about what makes for yellow parts. I"d give them just PH'd water for a feed or two till the problem resides then build back slowly with new ferts while diligently checking the PH and TDS.

Looks like magnesium without any other info. Your ph is a little high at 6.4 as well- add some cal mag and drop ph to around 6.0-6.2 to see how it reacts