If it were mine, I would pull the crank and look for dirt or a chunk of something on the bearing surface.
Are the bearings new? If so, check to see if they are marked with the correct size for the crank. I had an issue with rod bearings just like you are describing. Turns out the .001 that the shelf jockey pulled at the warehouse was actually .002. The "2" was a barely squiggly line which was mistaken for a "1".
