I have had some similar issues with mine when traveling and I found that the rear end of the Xducer had been bumped up a little too high. I moved it back down and the false reading went back to normal.
I run mine on the back of a pontoon log where it is difficult to access without pulling it out of the water.
After a few times of pulling the boat out to adjust it. I tipped the rear end down a little bit more than normal and clamped it down. Have not had any more false readings. [ Knock on wood]