This very small generation problem of MCreator has been there for a while now.
Procedure block 'Place at x: [number] y: [number] z: [number] structure: [your structure]'
(I didn't test it with other procedure blocks like this)
Problem with this is that the code itself generates this (an example):
template.addBlocksToWorldChunk(world, new BlockPos((int) (-6), (int) (-2), (int) (-6)), new PlacementSettings()
But ingame the structure is not spawning because the code itself is missing x, y and z. This would be correct:
template.addBlocksToWorldChunk(world, new BlockPos((int) x - 6, (int) y - 2, (int) z - 6), new PlacementSettings()
It would it make it way more easier if it would generate the code on this way. You can safe more time with this and do not have to do locked codes, which you have to redo after every update (relocking and then locking it again (to fix the error) + change it by hand again)
If you set position to -6 -2 -6 it will of course spawn like this.
Use x - 6 ... etc. in procedure builder to offset values properly.
https://www.youtube.com/playlist?list=PLAeL-oIFIEngf6S4p5X5CBd4GyWLUVaHA