Is rotobrush 2 incompatible with additional masks?

[led_bet]

I'm working in AE v18, using Rotobrush 2 to isolate some foreground elements in footage I'm compositing a person into. I've roto-ed these elements and I'd like to add an additional mask to these layers to hide a bit of the image too time consuming to roto with the brush (working with low-contrast footage), but are easy to hide with a tracked rectangle mask. But masks don't have any effect on layers with the rotobrush effect applied.

Are roto-brushed layers incompatible with masks (if so, why?), or have I stumbled upon a bug?

[Mylenium]

Not a bug or any of that. RB simply bypasses/ overrides the normal effects render order due to how it operates on the footage source itme. There's some other effects that behave similarly, even if it's annoying. Simply pre-compose the RB stuff and apply your masks in the parent comp.

Mylenium

[led_bet]

Hey Mylenium,

Thanks for your feedback. I tried pre-comping my roto layer and still had issues applying masks to the pre-comp. I moved on to a different workflow instead.

[jeromfischer]

Same problem here. Don't really understand why I can't use rotobrush and normal masking. It would make a lot of sense to use these two tools together to create a good mask. 

[jeromfischer]

Although pre-composing does work partly for my workflow.