When i try to save some Buildings to structure Blocks, i can save them and load them later via a Load Structure Block. But when i save the building via a redstone signal connected to the structure Block, i can load the structures in the same "session", but if i close the world once and open it the stuctures aren´t saved anymore. Also it doesn´t create the file for the structure in the world/structure folder when i save a building via a redstone signal.
You must use the interface to cause a file to be created. Saving via redstone only saves to memory for security purposes.