Opening and clicking any input field immediately after the structure block is placed breaks the UI.

If you place a structure block down, immediately open it, then go through into load or save mode, and finally click into any field, all the input fields will disappear as the block state will have reverted to "data" mode. Only works around half the time, and it appears to only have this issue when the block is in your main hand. See the video attached.

The second image is after quickly opening a placed structure block with NBT data.