Bug is such a bad word.
It is a unintended action from software when executing intended actions.
The fact that when you use the left side of an interface port for inserts and is steals away the right side is just, if you will a "mis-imlementation" of how the ports are handled and probably a "known issue" in house. Chances are this implantation is in
very old code. I know this is no excuse but dependencies very likely abound from changing the old code.
Go easy on Cakewalk. Sonar does a lot of things right if not this.