New growth dying? Why?

I would go with a good watering , so the medium is well hydrated. After that ( around 30 mins later) go with a feeding ( your regular feeding) if plants dont respond enough after 4-5 days go with acalmag product. I would go on slowly and just go with a regular feeding first. So it has the chance to regulate by its own. Using microbacteria and molasses is a good way to help the plants. They will come back soon. it just takes a time. If you feed your plants always do it in a well hydrated medium. You can start with water and beneficals ( molasses, bacterias, humic acid...etc. Then wait for 30 mins and feed your nutrients