The bug
If you are loading a structure from a structure block with a structure integrity that is less than 1.0, regardless of seed, it either loads every single block or no block at all.
How to reproduce
Use the following command and load the structure
/give @s structure_block{BlockEntityTag:{mode:"LOAD",integrity:0.5f,name:"minecraft:end_city/ship"}}
Looks like it is not rotation dependent, therefore I removed that part from the description. For me it loaded the structure after changing the integrity to a different value < 1.0.