Simple question--what version of SBPro introduced 'Generate Matte'?

I’m running 5.1, and thought I had the Generate Matte feature, but it does not show up as an option on my Layer menu.

A friend of mine who is running 5.5 has it, but I can’t find it.

Was Generate Matte not an option on 5.1? Did it get introduced between 5.1 and 5.5?

…or is there something I need to turn on in my settings/menus?


5.5 introduced Generate Matte: