Multimatte ID/Render Element - behind glass object (now occluded)

[RobPhoboS]

I'm sure I worked this out before but have completely forgotten (but could have been mental ray), and cannot find an old scene that I tested it with.
I currently have an object that I'd like to have the multimatte pass rendered but it has a glass object in front of it, which in turn is occluding it from the pass.
I'm sure it's a simple thing I have to change or do but right this moment I cannot figure it out


Crude mock up of what I mean:
Main render:


Multimatte render element:

[Yannick]

In your glass object in the refraction section, there is an option: affect alpha. I think this is what you are looking for.

[RobPhoboS]

In your glass object in the refraction section, there is an option: affect alpha. I think this is what you are looking for.

That's it !
Thank you Yannick
So easily overlooked when your rushing about.