Unable to set custom resolution + Assertion Failed on Video menu

[coleshores]

I know you guys are aware of the Assertion Failed on the video menu screen.
Id like to run at 720p since 1080p on my Tegra K1 has some frame rate drops in some places.
When updating the Game_startup.ini to I set :
sam_bFullScreen=1
sam_iScreenSize=1280
sam_iScreenSize=720
sam_iDisplayDepth=0
sam_iDisplayAdapter=0

and save it. It shows it selecting that resolution on startup but then some kind of autodetection algorithm bumps it up to 1080p. I verified this by setting 640x480 and the same thing. Shows on the window while going to full screen 640x480 but then renders at 1080p
Thanks in advance