If you are following these micro blast instructions:-
"Use 1-2 tsp Microblast per gallon of water, every 2 to 4 weeks"
I doubt thats the problem.
MOAB is probably your problem
"Combine 1-2 teaspoons of M.O.A.B. per 5 gallons of feed water. The amount of base nutrients may need to be reduced by as much as 50% when using M.O.A.B., over feeding may burn plants."
Did you try reducing your main feed by 50% (or more)?
Ive never used either of these products but MOAB is just a PK boost which will easily overfeed Phosphorous & Potassium.
Thus locking out all the micronutrients
Flush with weak flower nutrient and dont use the MOAB until later and then sparingly
Personally I dont use flower nutes till the 2 week of 12/12 as they need N for stretch