Hey it definitely looks like a magnesium deficiency, but I looked at your diary and you’re already giving cal mag so it is probably your PH. Best PH for soil is between 6.5 and 6.8. 6.0 is definitely a bit low. As you go lower than 6 micro nutrients like calcium and magnesium have trouble getting to your plant. At 5.5 they are completely locked out. I would try to get an accurate reading on your PH and go from there.