/locate always returns z=64

The /locate command always returns a z-value of 64 (or 32 in the case of /locate Stronghold), though the x-coordinate is correct.

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When I type the /locate command, minecraft show me the coordinates of the "structure" that I type (in this case "Village") but when I do the /tp command with the exactly coordinates, I'm teleport and the structure there isn't. I'm teleport in a normal place in the map. Same happen when I type "Mansion".