I made a sequence that adds variance between each 25 mL shot of water, and as I was editing the Farm Event I noticed the location variable has XYZ fields with no tooltip set to 0 by default.
Looks like those are input boxes for coordinates of a single location (custom coordinates).
I might have found a way to reproduce this faulty behavior:
Create a new FarmEvent using a sequence that uses a location variable with coordinates as the default value.