I have my own ideas of why but maybe you guys have seen or know of what can cause this.

2.3l stroker motor
Oliver Rods
Wiseco 1400HD 9.0:1 CR Pistons
Winberg 7 bolt 100mm crankshaft
clevite mains/ rod/ thrust bearings

Pictured below is the main bearing on the girdle side next to the front cover. Inside of the bearing is showing wear markings were the outside has no contact at all. The block main is fine with even wear pattern.

Motor was locally built from previous owner here in my home town.

I will be dropping the engine and rotating assembly off at the machine shop later today.