Sudden wilt from the rockwool being in the water all the time. Got to keep the RW up out the water and treat it like dirt meaning you have to let it dry from time to time.
different composition of the 3 part nutes are causing it to burn? happened to me switching to chem-gro so its possible imo. I would lower ppms even more 550 if you were to try to fix it and go back to veg.
You could try to foliar feed a really light ppm 150 once a day.
I doubt they will come back