Hi,
First, Thank you for the great works.
I have two bad issue with Volume.
1 : IR render, Volumetric material in a Cube. The render set black parts on Fur (or hairs, old cloths ... who have lot of plane with alpha channel)
2 : Final render, volumetric material in global volume of render setting. Fur (or hairs, old cloths ... ) are fine rendered ... but the background seems excluded of volume (hdr - Sky object). This is affect the lighting also.