Thank you for this.
The problem that I discovered was that I was clicking on the inherited interface function in the Child Class. That moved the inherited function from the Interfaces Group to the Blueprints Group, presumably so that it could be overridden.
And as you said, deleting that function from the Blueprints Groups sends it back to the Interfaces Group.
That initial behavior should either be disabled, or there should be a confirmation box alerting the user to a change in the function’s categorization.