GPU Lightmass: Point Light "Source Length"

Trying to switch to GPU Lightmass I’m getting some bad results, mainly when using static Point Lights. It seems that any “Source Length” is just ignored (while with CPU Lightmass it works correctly). This leads to the scene being lit in a very different way, especially when you have elongated lights close to any surfaces, like fluorescent tubes.

Did anyone find a workaround for this?