Fox farm ocean forest is fine. It just needs added perlite for more drainage.
I have grown hundreds of plants in it from seed to harvest with no issues that were not my grower error.
Over watering is usually the issue. That is what your first pics look like.
Transplanting stressed young plants never goes well and they are all in one pot now. Which may crowd one or two out.
Also looks like there are dry spots and the roots may be growing into hot dry spots and they are already weak. Transplants should be fully watered in.
Overwatering is about how often not how much water. Easy to drown seedlings fragile roots.
Proper sized pots should be watered to some runoff to make sure they are saturated then let alone til the soil is pretty dry and the pot is very light.
Must learn patience to grow.
Over worry and over care is user error. Its not the soil.
In fact i have tried a few different popular mixes and nutes and they all worked fine.
And i dont get layered soil. The roots grow down as far as they can from the beginning.