AM62A7: Tiovxmultiscaler ROI having no effect

Part Number: AM62A7


Tool/software: AM62A processor SDK v11.01.07.05

I'm having a problem with the tiovxmultiscaler gstreamer plugin - this is how I have it setup 

...
"video/x-raw,format=GRAY8,width=2592,height=1946 ! "
"tiovxmultiscaler name=multi "
"src_0::roi-startx=648 src_0::roi-starty=2 src_0::roi-width=1944 src_0::roi-height=1944 "
"multi. ! video/x-raw,format=GRAY8,width=1944,height=1944 ! "
...
My expectation is that this will give me square crop on the right side of my video frame, but I'm getting the same result with the third line completely removed:
...
"video/x-raw,format=GRAY8,width=2592,height=1946 ! "
"tiovxmultiscaler name=multi "
"multi. ! video/x-raw,format=GRAY8,width=1944,height=1944 ! "
...
It seems to me that the ROI is having no effect and I'm just getting my original image 2592x1946 squashed down into a square output 1944x1944.
 
Am I doing something wrong here?