Banding in viewport with 32 bit linear aces workspece and Color Management on

[Pascal Miller]

Hello, 

I am working in a project with 32bit AcesCG Working Space AMPAS S-2014-004, with linearize working space on. 

My color management is turned on (Simulating HDTV Rec.709) and I'm looking at all this on my BENQ PD moniter that has a rec.709 profile on it as well. With a simple feathered mask, I get very noticable banding in the preview window. 

When I export an image however, the banding is gone, or a lot less. What do you think could be going on?

Thanks!

Pascal