In case this information helps, I'm finding that structure blocks will not save or load in 17w49b either.
I've set up my save block with correct dimensions, and then click the save button. No message appears to confirm the save, and no structures folder appears in the world save folder. I tried to add the folder manually and save again, still nothing. I added a load block and tried to load the structure, but it wouldn't load. In fact, there wasn't even a bounding box showing for the load block.
I also tried starting a new world and doing the same again, to no avail.
A Doe
In case this information helps, I'm finding that structure blocks will not save or load in 17w49b either.
I've set up my save block with correct dimensions, and then click the save button. No message appears to confirm the save, and no structures folder appears in the world save folder. I tried to add the folder manually and save again, still nothing. I added a load block and tried to load the structure, but it wouldn't load. In fact, there wasn't even a bounding box showing for the load block.
I also tried starting a new world and doing the same again, to no avail.