Hi I'm in Dallas TX

Planted 5 shantung maples last year

3 are doing fantastic

2 have plenty of buds but haven't leafed out…

When it dies leaf, the leaf is brown and very small

What could be the cause of this?

any ideas?

Pictures?
My first thought is always... how were they planted, & what soil conditions at your house...

When I was in Dallas, I noticed a lot of heavy clay...
It's been raining a lot more than usual... Trees might be sitting in a basin of water...

Some plants like growing in a bog, not sure about your maples.