my guess is that you never could “delete” them before. What we called deleting was actually just the same as what is now called “initialising” but the introduction of the editor actually shows the status whereas the old version didn’t.
I did revert to 7.1.5 to check this and you are right. The "empty" performances in RM can't be selected by RM unless you chose to "create a new performance" but they can be by the Remote and show as "New performance". This make sens, otherwise how could you create a new performance without RM connected ? Thanks for your lights