Do you use any mod that make blueprint instant when you place them ? if yes, it migth be the same things as https://mods.factorio.com/mods/Earendel/aai-programmable-structures/discussion/17197 The Creative Mode mod does precisely that, that's probably the issue then. I'll see about having it not do...

Finally registered to report a bug with scanners: In "complex" setups, when removing the scanner the signal input and output terminals will remain and become unremovable: aai-remaining-terminal.png 0eNrtWluOozgU3UrJH/MVR9iEQKLullrVv7OCUQkRcFJWgUHGpDtTygJmH7OyWcnYIW8wYEiq01L/VAmwj6/vub4v5x0...