US Mk14 fish always ran deep at the start of the war. ALWAYS. The Navy was too cheap to test them with a real warhead, and used a dummy that was significantly lighter. The average value of this was 11 feet as I recall.
In addition, the magnetic pistol failed
often. More likely than not to fail.
On top of THAT, the contact pistol was ALSO faulty. If they hit close to 90°, the detonator would break and fail to explode.
Read some early war patrol reports—they sound a lot like your post
