Some balls are, seemingly, not legal per the game but allowed by the editor.
The valid one below is a "bred" shiny with a Luxury Ball. The Illegal one is identical but uses a Love Ball. Both are considered legal by the editor, but the game finds issue with the Illegal one.
909 ★ - Fuecoco - 53890C76154F.pk9
ILLEGAL 909 ★ - Fuecoco - 53930C76154F.pk9