adc0 overloads

[Stevejxl]

Just took delivery of an Anan G2 and running the latest Thetis build (v2.10.3.8).
I am experiencing frequent adc0 overloads with very distant lightning crashes (on any band) or large, fast-rise time signals even with the attenuator set to 30dB.
I am also experiencing audio that sounds like it is passing a "dc" component ('tinny" hollow sounding) with large signal peaks.. Much like peak distortion.

I am new to Thetis and hoping this is a "pilot error" setting issue..
any guidance here would be helpful..

Steve