Structure block not loading structure from 1.12 in 18w11a

I used a structure block to save a structure of mine in 1.12. When I went to the 1.13 snapshots, I backed up my world by copying the whole save file (which includes structures). In the backed up world, I place a structure block and it when I try to load my structure it says its "not available".

It works if the structure was created in the snapshot version I attempt to load it in.