You must be running SystemBuild on a Windows Remote Desktop instead of directly on the computer where MATRIXx is installed.
The large circles are connection split markers which are sized to be a certain percentage of a font size. But, the font size returned
by Windows is much larger on a Remote Desktop than on the native machine.
Try displaying the same SystemBuild diagram on the native machine and the connection split markers will be sized correctly.
This bug is fixed in MATRIXx 7.2.0 which will be released shortly.
Thanks for the reply. Yes you are correct, I am running on a Windows Remote Desktop. I'll update when the new version comes out.