Ok. I figured out your problem...Lack of patience.
Tiz bad juju cutting 'em open this late into flower. The plants will tend to get even. Couldn't you wait for help or instruction? Might have been as easy as lifting the rootball and adding some fresh soil. perhaps a transplant into a larger container. Surgery this deep into flower is for dire emergencies only.

Oh well. If they start to look too stressed, raise the lights a tad for a few days.

Your mix has perlite, and is a peat-based product. It"s ph buffered, and contains organic nutrients. Y'all gotta get this soil/soilless thing out of your heads. It'll mess ya up forever, lol.

If 6.8 ph is your accurate runoff number, that's about perfect. At least you're not using color coded drops.

A nutrient schedule is just that...a schedule. When I was using the MG, I was also giving 1/4 strength twice a week, but it is best to do so consistently. Inconsistent nutes promote inconsistent growth and deficiencies, or conversely, you can easily OD them. Plus, every once in a while they like properly ph'd freshwater if possible.