Anybody else tried ARB_instanced_arrays with NVidia 285.x?

Here, geometry instancing with instanced arrays works fine up through 280.x (280.13), but starting with 285.x (285.05.09), the pipe's obviously not reading the vertex arrays right as I get splittered triangles everywhere. However, non-instanced rendering works fine.

GTX285. GL 3.3 compatibility context. No GL errors.

Just thought I'd ask before I spend much time with this.