So far, I have only seen this happen with enemy Ironside Hard AI on Red Rock.

What happened is that sometimes his Dozer will 'teleport', or move at extreme speeds, to a build location. I noticed this when I was wiping out his ally's base and destroyed his WF which he built directly on top of a Supply Zone. I turned my back for not more than half a minute and I saw a WF, 50% built at the same spot! I destroyed the half-built WF and tried to target the dozer building it, but as soon as my first ordnance is about to hit it, it teleported elsewhere.

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