Hi Maru I'm now using version 1.6.2 and now the opposite is happening. The lights reflection is white in the renders alpha channel (as it should be), but in the beauty pass it's showing as black.....
[EDIT] Strangely it's now gone back to the the previous behaviour of subtracting the lights reflection from the alpha channel [EDIT]
I've also tried turning shadow catcher illuminator on, but this just seems to stop the light reflecting at all in the shadow catcher...or even more strangely, intermittently has no effect at all.
steps to recreate.
- Create a plane.
- create a corona light and place near the plane.
- create shadow catcher material with enviro/backplate set to black, alpha mode set to "for compositing" with reflection properties level 1, colour white, fresnel 999, glossiness 1.
- corona render settings set direct visibility overide to black.
- run interactive render, lights reflection is subtracted from the renders alpha
- turn on shadowcatcher illuminator checkbox and check bueaty and alpha passes in the render window (nonsensically, sometimes this gets rid of reflections sometimes it makes not difference.)
I should point out that everything works correctly when choosing alpha mode "always solid".
Please see attachments for better understanding.