My structure seems to be placed, but no blocks are placed in.

I'm learning how to generate jigsaw structures so that I can generate dungeons for my project. I'm working in 1.21.5, with data pack version 71. As a first step, I've just been trying to get a single structure to generate into the world. I've followed the Minecraft Wiki's documentation on structure generation and as far as I can tell, I have the four key files to generate a structure (included in a follow-up post): structures/foo.nbt, worldgen/structure/foo.json, worldgen/structure_set/foo.json, and worldgen/template_pool/foo.json. As a preliminary test I just tried placing the structure with /place structure, which successfully autocompletes to find my files and the game says has been successfully placed, but nothing actually gets placed into the world. I also tried generating a world with the datapack included to see if for whatever reason it would successfully place them during world gen, but that also didn't work; however, the /locate command can find the structure in the world, but teleporting there shows that nothing has actually been placed at that location. (It also is not being placed at the bottom of the world, I checked). I thought that the NBT file itself might be empty, but it does have data inside. I couldn't say whether it's corrupted or not though, I can't interpret NBT binaries. Re-saving the structure and replacing the NBT structure file did not fix the issue, though. At this point I'm not sure what could be going wrong, I've all but copied the tutorial files from the Minecraft Wiki's tutorial on custom structures (https://minecraft.wiki/w/Tutorial:Custom_structures) and nothing will generate. I'm hoping someone can point out what is probably some obvious mistake for this noob. -_- Thanks in advance for any help!