I would let them dry out and feed gently
You have figured out that it's not a Ca or Mg deficiency.
You have tip burn and brown leaves that tells me they have been overwatered,the roots have been compromised and the salts are building up because the plant isn't using them. Straight water sparingly and they will like you. Adding something isn't your issue,they just aren't utilizing what is present already. You and others may disagree,just my 2 cents.. Best of luck.
Let them dry to almost point of wilt and then straight water a few times and see how they react.
