Axiom not marking fish

[JimBognr]

I have been trying to locate fish with the sonar, but cannot see any fish. I also have a third party fishfinder at the helm and it shows fish as well as the other features below the boat. The Axiom is at the front of the boat with a transom mount transducer. I see features as I do on the third party fishfinder, but no fish. Bottom, bait [censored], etc. are clear.
Also, I was fishing in about 30 ft. of water and the axiom went crazy. Lost bottom, full of interference, etc. I rebooted, reseated transducer connection, and powered off the third party fishfinder. Nothing helped. As I moved from the location, the symptoms dissappeared. When I moved back over the same location, the symptoms reappeared. I was in a strip mining pit the varied from 10 to 50 ft. depths. Could have an underwater object be the cause? All sonar settings are on "auto".