Last year I moved a Magnolia tree from a shady aspect and replanted in a sunnier one. At first it did okay but this year all the budding leaves are discoloured and fall off almost immediately. It's now completely bare but with plent of leaf buds. Can you help?
It could simply be that it's too dry (are you in the UK?)
Any newly planted/transplanted tree ideally needs to be kept watered for the first year of it's life.
Make sure the ground around your magnolia is kept damp (assuming you don't have a heavy waterlogged soil)
and you could use a tree & shrub food but don't overfeed.