Star of Bethlehem ... healthy one and sick? patch

Edit: Growing under Japanese maple and maples are notoriously difficult to grow anything under due to surface roots and dry shade ... heavy leaf cover transpires water AND prevents rain from falling on ground.

Any ideas why the brown bits? Both are shady, the brown bit ones may be overcrowded?
This one is in a very dark corner.

 

These are under a maple tree in a fairly shady area.