Easy fix ... toss MG .
Water ffof with 6.5 water .. run it alone.
Since you might have added a bit too much nutes in an already hot soil , just water ( when needed ) and let medium exhaust a bit. Plant will feed fine from it .... its fine , no worries.
Later , you can SIMPLY use more FFOF as a topdress ( adding a scoop or so ) and water in.
There is so many growers that seem to hit a wall using FFOF , for some reason. It can be recharged this way for any length of grow whether photo or auto.
MG is notoriously hot ( extended feed ) ... it pushes nitro heavily thru its use - not so great during flower.
Some growers use it , some hate it. It just when its added to already nuted medium where some things happen.
Anyways .... IMO i would just water it ... even for a couple weeks. If plant gets hungry , top dress it and continue water .