The bug

In multiplayer, structure blocks cannot select areas of more than 32 blocks. If a number is greater than 32, it will be reset to 32, except for the "DETECT" function.
If you use it, the selected area will be displayed correctly and written into the structure block. But as soon as you press "Done" or "SAVE" it will be set back to 32 blocks. Also the saved structure has a maximum size of 32x32x32 blocks.