Probably some of the leaves were damaged in transit and during planting too, which are the ones turning brown straight away. However as ian said, the plants are grown out of the water to speed up growth, then when they go to the LFS they get put into water and will be in water in your tank. Therefore the plants will go through a "transition" phase where it changes from emersed growth to immersed growth. Likely most of the 4 leaf clover shaped leaves will die off in this time, and many do not get them back, with new shoots only having one or 2 leaves on them.