Sorry I couldn't get my screenshots working, but there's box piles on Gazalas Sidi Muftah flag. The large ones, maybe 1 cubic meter in size, right next to bofors. They bounce all HE and AP shots, even if shot at flat 90 degree angle. HEAT rounds however seem to explode on impact as they should.
This just came back to my mind, since some other players today were reporting arty shells bouncing off wooden fences on Port en Bessin. Maybe there's something wrong with their materials?