Structure blocks loading with a fractional value in the 'Integrity' field either fail to load the structure or load it completely without integrity applied. Which outcome occurs is determined by the location of the structure block in the world and the integrity.

To reproduce: save any structure in a structure block and reload it with integrity set to 0.5.

repeat at several different locations. 50% of locations will load, 50% will not, as per the 0.5 fraction.

the position of the structure block, rather than the position of each individual block, seems to determine whether it is removed in accordance with the integrity setting