It's better call operator fault not L-rod, please don't outrage L-rods.
Geo !!
as we know you have built a good acoustic type LRL like PD, why didn't use it?
of course now I use L-rods without F-generator only for depth determination.
after locating and pinpointing a treasure with my fabulous PI (MDL) I check
there based on thumbs rule to find approx depth. ( I stand exact up the point, set them parallel and start to
walk until rods cross or diverge), one of our treasures is at about 14-16 meters depth, another one 9-11m. our another PI which is somehow more powerful than pulse star, over these points is entirely silent, mute.
so maybe Aft is right, treasure is at great depth, but behavior of your MD for a real treasure is different than trashes. you should be familiar to this behavior and in such areas at first scavenger there from any kind and piece of junk with small coils, afterward search with bigger and bigger coils to see what can bit; I'm sure you knew what I'm telling .
oh forgot to say MDL is entirely useless in such areas where are full of junk metals cos it beeps nonstop at overload level
and the worse for metal building foundations or columns.