There seems to be a bug in Sierra's Xquartz and/or OpenGL interface. We have been able to reproduce this behavior on a virtual machine here, so we will be able to try out some things. As a work-around in the meantime, consider keeping the object controller permanently open by making this the first DriveSuma command.
DriveSuma $NPB -com surf_cont -view_surf_cont y
If you need to move that controller to a specific location on the screen, you can do this by driving suma to put the controller in a specific spot. Create a small file with just these lines:
cat contxy.niml.vvs
<Viewer_Visual_Setting
ContX = "200"
ContY = "1000"
/>
Then move the suma controller to that location with
DriveSuma -com viewer_cont -load_view contxy.niml.vvs
