Sub-surface Cheat/Glitch in Watch_Dogs?

So I was just starting a tailing session and tried to locate the target. But my direction indicator indicated him to be about 100 meters below the surface at a poker game, the one in the shed in the suburbs.

I left the house where the poker game is and suddenly the other player profiled and then shot me. After that, the game showed me his outline, he really seemed to be far below the surface.

How was he able to profile and shoot me through the ground. And how did he get down there? Is this a glitch or something? I was not able to find any information on it online, can anyone help?

If this is a glitch or cheat, can I report somewhere that I was cheated?

Update

An answer (that has since been deleted) reported the same incident. It also gave a possible hint how to reproduce the glitch, reporting to have witnessed the target rapidly jumping up and down in the poker house. Maybe this will help us find out how to recreate the glitch so it can be fixed.