Fusion
Never tried deleting an appearance so not sure why Fusion would throw that warning. All I did was drag an appearance to a component and let go of my mouse button. Never hit my delete key or right clicked on an appearance and hit "unasign and delete".
Which is funny cause I'm gonna make another bug report in a minute where I'm unable to delete an appearance it is linked with an applied physical material but I DON'T get a warning...
