I have a related problem. I usually ignore the whole question, but today I have plenty time to rig stuff, so I´ll ask:
My setup: Resolume Arena @1920x1080 via syphon - > MadMapper.
Problem: In Projector Tab of MM, the screen default said 1024x768. When unlocking aspect ratio and changing values to 1920x1080, my output frame is unchanged, but the Projector window (yellow) overlaps the output frame. See attached image for description.
Maybe I´m mistaken. But shouldn´t "output size" be same as my input size 1920x1080? (apologies for the gigantic screenshot. TinyPic.com does it that way)