You mean you forced an M-key drive to go upside down into a B-key slot despite the misalignment of the key? I think I've only ever found B-key slots in adapter

You mean you forced an M-key drive to go upside down into a B-key slot despite the misalignment of the key? I think I've only ever found B-key slots in adapter cards that have one M-key slot for an NVMe drive and one B-key slot for a SATA drive, but it would be hard to miss the distinction when they're right next to each other like that.